How do you come up with stories and comics that you're too excited about to put down? - Very simple. Discipline. No one will absolutely love their story at all points. This is the problem behind waiting for "inspiration", which is in effect what you're doing. That, and it seems you've having some trouble with your own self esteem in coming up with a story. What you need to ask yourself, and I mean truly sit and ponder on this for a while, "why do I get tired of my own stories?"
As for them lacking a "real story"? Says who? No story is ever, EVER thought up wholesale and complete upon its first conception. No story survives the creative process unchanged from the initial thoughts that get it down on paper. Perhaps it's a problem if perception and expectation that you're having?
As for coming up with characters and OCs first. This is not a sin as some would claim. Contrary to @CarltonIsaac, I'd say you can easily come up with characters for a character-driven plotline first. You can develop a good story if you have a good character and know them intimately. Do you do character bios? Do you write full backgrounds? Personalities? Likes, dislikes? Secret thoughts, idiosyncrasies, tics and habits? Have you determined their upbringing, and fleshed out the milestones in their development? Events that have shaped them into who they are? Are they right handed or left? Are there any minor or major injuries or defects in their physical prowess that would influence the way they interact with the world?
When you know who you characters are, you can determine that motivations drive them, and perhaps come up with something to base a story around. Do you have a character that's a pathological liar? Well you've got a great basis for a story that explores and deals with the actions and consequences of being a pathological liar. Have someone with an ego, and someone naive and trusting? Great chance for some stories there if you pair them up.
It's not a matter of "why I like my characters so much." I have characters that I absolutely despise sometimes writing about them, not because they affect me personally, but because it's not something I'm resonating with at the time. I push through it anyway, even if I leave a note to myself that this part was half-assed and needs further development.
Writing and story telling are not Just Talent. They are skills, and like all skills they can be trained. Someone with a natural affinity for something will always be surpassed by someone who puts their 100% into developing and training their skills if they don't train it. They may have an initial "boost", but in the end "natural talent" counts for extremely little.
To give you a little inisght, I'm a pantser. I've always been a pantser. I was surrounded by creativity in my youth, my family got me into D&D when I was 5, though even before then they encouraged whatever creativity I came up with by, as a toddler, telling THEM bed time stories (because the "normal ones are kinda boring now I heard them too much"). I started "writing" in second grade, first for a Halloween project (write a scary story). I'd always loved to read, and would read almost anything from any genre. I never planned anything out, came up with a concept, and went from there. Still do that to this day, and so far it's working out great. No, I never publish the first draft, that's not what Pantsing is as some salty plotters would tell you (insert writing group war flashbacks here). I also have an intense burning passion for science, and the only reason I'm a writer and not an engineer, chemist, or physicist, is because I was led to believe that ALL SCIENCE IS MATH and that, because I don't particularly process math the way school wanted me to in the 90s, I would never be able to get a career in my original dream jobs.
Going back over my ancient works from before I was, say, 10? I can remember each and every influence in that piece. I was fascinating reading over some of my old stuff and tracking my progress over the years. As I was exposed to more stories, more variations, more content, the better my stories got. The more I wrote, the more I experimented and exercised the writing muscle, the better crafted my sentences were. The better I was able to utilize the vocabulary and concepts I had internalized. Every new scientific discovery, every philosophical question, every bit of science, fringe science, and pseudo science I learned about gave me new elements to weave into my stories.
To which I ask you. Do you read? Do you study interests outside of writing? Do you have other hobbies? What are the influences on your work? Read and read often. Read wide, and read deep. Find the passions you're interested in. Study, practice, read, train. Everything you do and experience in life will only serve to increase your storytelling capabilities. And remember, the first draft is never the publication draft. Revisions and editing exist for us to polish the rough sculpture we initially create. You think Michelangelo created such beautiful sculptures just by smacking the marble a few times? Hell no, even sculptors will ofttimes do a few practice sculptures before working on the main piece. Consider the drafts your practice blocks.
I have two exercises I'd suggest.
1) Character Q&A. Come up with some questions to ask your characters. Get some questions from friends. Sit down and "conduct an interview". If you haven't come up with some details yet, just letting whatever comes out of your character's mouth can fill them in. Don't think, don't consider. Don't go "Oh, but he wouldn't do/say that!". Just let them talk.
2) World build. While you can get a fairly good character-driven story out of just the base characters alone, it's much easier to have an environment that you can draw elements from. So? World build. There are dozens of, hundreds even of videos and blogs dedicated to world building. I find the ones for tabletop RPGs like D&D the best, as most of the ones i've come across for writers tend to be a lot less granular.
Beyond that, something I've come to understand in engaging with writers in groups and forums over the years, is that there are really 3 ways of crafting a story.
1) Plotter - The one who will spend most of their time making a book in actual research, plotting out the story each and every step of the way. Can get even as extreme as determining what the characters will do and think during the outlining process. Characters are slaves to the plot, and in my experience much of the time the character can feel a little too cookie cutter, a little too structured and robotic. These tend to be the ones that get the books done the most often, as the story is often written out before they even start writing it, it's just a matter of applying the dressing for presentation.
2) Pantser - The one who will just write things as they come to mind. Usually doesn't have a lot of structure, and most of the time making a book will be spent editing out unecessary parts, filling holes, hunting down lost plot threats, tying off loose ends, and in general a lot of re-writes. Mostly for continuity. Characters are inserted, created, and developed as you go. The downside to these types I often notice tend to be, as I said, lost plot threads, gaping plot holes, continuity errors, and the like.
Those are the two most commonly accepted methodologies. I'm sure I'm not the one who started this third, but I never see it spoken about beforehand. I started doing it when I started writing stories in my homebrew D&D worlds that I would always come up with for campaigns, but those campaigns would always die because my groups tended to... Not last long.
3) World Builder - The one who designs a world, then decides what stories can play out within it. Usually the style that has multiple stories in the same setting, often disconnected from each other. Can be as simple as coming up with the world, the rules of the world, a few nations and cultures and a bit of geography and go from there. Can get as granular as filling out every town full of shops and "npcs" your story may never use.. The way I do it, admittedly all I can tell you as I'm the only one I know to do this, I like to come up with the history and rules of the world, for at least a few thousand years, in broad strokes. Fill out a few nations and cultures, populate with species, etc. Then I start looking around for interesting story potential. Political intrigue, wars, otherworldly invasions (I write fantasy and scifi mostly), etc etc. Sometimes, if the world is created very granular, I'll just come up with some characters that seem interesting and drop them in to see what happens. This method's worked out well for me so far, and for reference I do mostly pantsing, with a little plotting.
That's a lot, sorry. Hope this can give you some insight that you can utilize.