What are you trying to write exactly? Are you trying to make a novel (and if yes, which genre)?
Do you have some examples we can look at? It's probably easier to give pointers if people can read what your writing is like.
From what I understand regarding the feedback you got, I think the problem lies more in the delivery of the plot and scenes of the story rather than the choice of words. I'm not a novel writer myself, but I think that they maybe mean they can't really follow what is going on. Do you have a plot that you use for your story (as in you know how your story begins and ends and what happens inbetween)?
I don't know if changing and altering the words is really going to solve your problem. Using synonyms can make sentences a bit less repetitive but it also brings the risk of people not understanding the word and getting even more confused (this could especially happen to readers whose first language is not english).
Quick tips with Kuma
1. Be sure to get your story straight.
At the core of every tale, there is a guiding element that allows you to build on it. You can call it the "Thesis" of the story. Basically is the message you want to convey to the reader. If you have a clear idea about what your story wants to be about, it will help you when it comes time to write it.
2. What and How
You can split how you tell a story into What and How.
What is the previous point "What's the point you want to get across?" "What's the message of the story?" "What does this scene mean?"
How is about how you implement the philosophical aspect of your story. You might have a great idea, but if your execution is piss poor, then if will lose its luster. You can have shit ideas with great execution, but not the other way around.
3. Characters aren't people.
When you write you might feel compelled to make your characters as complex and "realistic" as you can. Scrap that. Characters aren't people, they are vehicles for the story's message and plot. They will develop, they will evolve, but functionally they're part of the environment. Don't be afraid to make the chew scenery, don't be afraid to use a bit of exposition. If you attempt your characters to be as life-like as you can possibly can, then some information will be lost, unless to use paragraphs of description to explain their inner life and expressions. Think about theater, how every expression and feeling is amped up so the people, even the ones at the back of the house, can appreciate it.
4. Worldbuilding is King
When you write Fantasy your story will live or die on the back of how interesting your setting is. You can go full generic with the classic narrative clutches, like making elves bow-wielding, forest-dwelling, surprisingly clean hippies. That's easy, people see an elf on a story and automatically think Tolkien. If you want to go at it cheap and fast you can use these kinds of shortcuts. But if you want to attract attention, go for broke, develop a living breathing world. Question yourself about things that seem like common sense to you and trace their origin. Like for example, think about how many Fantasy worlds, way different from ours, have the same weapons as our history. But how can that make sense if their world evolved differently than ours. How did swords turn into such idiosyncratic weapons? Try to give the elements of your world that have evolved from their own history and development, not just copying our own and using it for its familiarity. There should be a degree of familiarity, just to avoid alienating your readers or spending 2/3 of your chapters explaining lore, but there should be enough weirdness to draw the readers into your world.
I know this advice gets thrown around a lot, but really, reading can be a big help. Take books you like and examine how those authors handle word choice, dialogue, description, scene transitions, character arcs, etc. Not just what words they use, but how they use them (when do they use simple words? when do they use complex ones?)
You don't have to love reading or read every day, it just helps to look at what others are doing.
Oh also it's totally fine for your first (or first few) drafts to be "bland" as far as word choice goes. If there are words you want to change because they don't have enough "umph", or because you realize you're using them a lot and want more variety, it's fine to just make a note of it and change them later. You don't have to have a dictionary memorized or know exactly what words you want to use at any given moment. I make a ton of "[describe this better]" notes in my own writing lol.
thank you for telling me the flaws. i will see if I can change anything while still being more expresive
thank you for that. i am actually reading the whole harry potter series at the moment . currently in the first book. I will try to read as much as i can
Op I think the best way to go about this is to read other novels that you love and study how they got their structure and wording correctly. (even just other media in general, not necessarily novels)
I get the vibe from your post your problems are with structure and not necessarily characters or world building.
And just writing more often should also help.
I have this tumblr post with a ton of resources on writing saved, I hope some specifics in here can help you as well https://referenceforwriters.tumblr.com/post/44138372816/masterlist-of-writing-help-for-writers3
I began reading Chapter 0 and one of your problems seems to be that you're using unnecessary sentences. One tip often given to new writers is to short your sentences and say what you want to say with less words. Compact writing bears more impact and makes losing the reader less likely. Avoid word repetitions (in chapter 0 you've got 5 forms of "begin" in the first paragraph for example) and don't say the same thing in several sentences.
I hope this was understandable. I'm more used to giving writing advice in German 
I second the point about reading a lot. Read constantly. Read broadly. The way you improve at something as instinctual as writing and language is to immerse yourself in the work of others. That's true for writing, for art, and for music.
But also, make sure you're reading good writing.
While there's nothing wrong with Harry Potter - it's one of my favourite fantasy series - Rowling is pretty ordinary with how she uses language. She writes with clarity, but with little poetry. This is true of a lot of YA authors. If you want to learn to write in a way that doesn't feel bland, you need to read authors who write in diverse ways. Two good ones to start with, who are both fantasy writers, are Neil Gaiman (for beautiful prose and turn of phrase) and Terry Pratchett (for wit). There's a lot of old sci-fi which is stunningly written as well. Kurt Voneggut springs to mind, I love his use of language.
thank you for the suggestion. I chose harry potter cause it's the only movie I saw which had a book. so it would help me see the details while remembering the movie. i will try your suggested books as well
Seconded neil gaiman. And i am not a native english speaker but even i knew as a child harry potter’s prose is kind of bland. Harry potter was one of my fav series too. Meanwhile about the thing-that-should-not-be-named, I need to execuse myself now, said dumbledore calmly.
Hi there! I am a newbie writer myself and I write about fantasy (the kind that shifts from medieval to becoming a pseudo medieval plot in my novel).
I read and saw your book and it looks promising. Why? For me, you are already sure that your novel Void Requiem is your first passion project as a writer. You love the scifi-fantasy genres so you incorporated that into your own story which was very evident especially that in the beginning you started off with a fight scene happening in your novel's genesis. It may be a brief one since entertaining fights have to be described with your five senses (sight, smell, touch, hearing, and taste like "as I slashed his chest, his blood splattered across my face with my tongue tasting its disgusting saltiness before I could wipe it cleanly from my mouth").
You're also clear that from your own blurb, you intend to have a strong male lead as the MC of your story. But its also important that you do world-building first before you begin writing your story.
Sure. World-building does prevent a writer from writing one's own story immediately because world-building demands a lot from writers like geography and maps, ethnicities and species, magics and artifacts, and all those things that will force the reader into your story but it doesn't have to go straight to that devastating point. You only have two episodes which was why I am saying this in the hopes of you not making my mistake.
When you begin world-building, ask yourself "Is Void Requiem plot-driven or character-driven?"
Do you want us readers to get to know your novel through the plot/script that you established already or do you want us readers to get to know your novel through your MC(s)?
From what I've read in your two episodes combined with the blurb, you should be making your story character-driven. I am not forcing you or anything but this is based on I've noticed.
Of the three tags you've posted, this tag #space_adventure should help you answer that question. Who's space adventure are we talking about? Knowing who's adventure it is, it means we should see Void Requiem's world through this MC(s).
When you world-build, make a world that will shape/force the MC to become the universe's next overlord. A world is built to matter, affect, and transform your character(s). So far, you've got one and there are no other POVs. Harry Potter is character-driven because it focused on his childhood and how he entered the wizard world. He is also a good example of how the world-building is seen through him as the main character. This path is more immersive than plot-driven because we relate to the human/MC character rather than that plot (which isn't human but simply made of paper, word doc, scrivener page, or rotten data).
If you decided to make Void Requiem more plot-driven where everything is set and you just need your actors to do their part, then its your choice for introducing your world to us in that way.
I'll stop from here and feel free to tell me if I'm wrong or not but I really want to know how Void Requiem will turn the MC into the overlord of the universe. 
Thanks for this thread!
P.S. My advice is sourced on what I've learned from a Youtuber named Abbie Emmons.
thank you for the detailed comment and yes it's mostly going to be character-driven but not just the mc but also other figures. at the end of the day, the mc is just one character of the whole world. His impact on the world will be greater each time but for the most part, other key events will take place without his notice. That is my overall goal of telling the story. He might want to become overlord but he is in no ways the center of attention (at least for the most part) As for how he becomes overlord...that will be a secret for now. Again thank you for the comment