I think what everyone else says is true, re-reading your own beginning can make you feel like your story is worse than it actually is -- but not just because you know what will happen. It could also be that you have grown as a storyteller since you started your comic, and now your brain is looking for how to take it to the next level. You've probably hit a similar feeling in drawing -- most of us have! -- where all your drawings suddenly look bad because your brain and your understanding have grown faster than your skill, and you have to work to catch up. When you reread and your brain tells you "this is so boring!" what that really means is "I'm suddenly realising this could be so much better!"
But okay, reading your comic so far and specifically looking for stuff about this, I think the biggest thing that might be hitting you is that there's a lot of explanation BEFORE we start getting to what's interesting about the characters. We get caption boxes about the world and how studios work, we get explanations in thought bubbles about magical girls, and we get lessons about how to handle a magical spear -- none of those are the things that are super intriguing without context.
There's a lot of very basic, surface-level emotion in the first couple of chapters that don't tell us much about the characters. If I saw on the news that a disabled woman had her family heirloom taken by debt collectors, I'd be like "aw, man, that's awful," but I wouldn't identify with her family in any meaningful way -- we need to see who these people are in order to sympathise with them, not just that they're in bad situations. Valencia is embarrassed when she's laughed at and she's sad when a sad thing happens, but I don't know much about her.
Heck, the most INTERESTING scene is told to us in an off-handed aside -- Valencia discovering she has a magical girl marking and deciding to hide it from her mother, not because she's ashamed, but because she doesn't want to worry her. Her mother's reaction makes it clear why Valencia felt that way -- becoming a magical girl isn't what she wanted for her daughter; it's a burden. That scene where her mother cries and says "I'm sorry your life turned out like this," in a single line, tells us more about magical girls in this world than any caption box!
And knowing what becoming a magical girl means to her tells us a lot more about her character, too. Not just, "she's poor and this will make money for her family" --- I mean, this is a weird, secret power that she's hiding from her family and trying to master as a last ditch effort to pull her family through. That tells us something about her and lets us see through her eyes and sympathise with her, as opposed to the very beginning, where we watch her go through the audition with no idea of how secret, scary, and different this is for her.
Ultimately, it isn't just the story revelations and plot twists (Isaac has some kind of power!! Valencia is a post-birth magical girl!) that are interesting to us, but the characters, and whenever you can, you want exposition and explanation to tell us something about those characters. Isaac monologuing to himself about Valencia's power gives us a lot of information, but nothing about the characters of Isaac and Valencia. But if, for example, Isaac instead just looked a little sad after she summons a spear and says "You're more powerful than you realise, Valencia...." then we'd understand that he sees more to her than she can see, and he sort of wishes she could see it, but he doesn't want to tell her directly -- without any thought-balloon monologuing. Alternately, if he grins like a salesman and keeps up a "you're goin' straight to the top, kid. You'll be a magical girl in no time. You're our ticket to greatness." patter then that would start to suggest something entirely different about his motives.
But since he and Derek are mysterious, and we don't see anything of their motives, that, weirdly enough, makes them less interesting.
I don't say all this thinking that you need to rework anything -- I think most webcomic artists feel like they didn't really hit their stride until a couple chapters in. But now is a point where you're starting to get to the good stuff, and thinking about things like this -- how to use explanations to reveal character, what makes a character interesting, etc -- can make the good stuff really exciting. Going forward, you can really think about how you reveal information, and when you have chances to show who your characters are, and give them moments to break out of their tropes and show us another side of themselves! I don't think your story is boring!! you have a lot of intriguing stuff to work with, so I say, use this moment of examination to take it to the next level as you write new chapters, and really make your story the best it can be!! : )
