itch.io

First of all; let's stop talking like your idea is the objective truth and the best scenario in the world. Just like I speak based on my preferences and what I believe is the best, so do you. 

Second of all; "the story just has two chapters" argument doesn't work here. In an average book, that still would not be acceptable, because, unless you're a widely popular author like Sanderson or G.R.R.M. then, never mind the first two chapters, you only have the first three pages to hook your audience in. It especially doesn't work here, because while a book's first two chapters are 10k words at most, the story we're presented here is 350+K words, equal to two and a half novel. If you trim all the alternative texts in the story, it would still make 150K+ words at worst, equal to one big novel.

Third of all; I do like child protagonists. If done right, they can add a different nuance to a story. What I don't like is how little they always have going on compared to an adult protagonist in almost any story. They have very little agency to sustain the reader for a long period of time, and they can only explore a little variety of topics as opposed to an adult protagonist that can go through many directions. And when a story tries to put a child protagonist into the shoes of an adult one, it most often goes with an even more bizarre taste. 

Fourth of all; agency. Agency is the one thing that will keep you actually interested in the protagonist of a story. When you read a story, you expect the protagonist to do some shit, preferably cool shit. But when, like in many cases of child protagonist, the protagonist loses the agency they have due to their age or some other reason, the story becomes a chore to go through in order to reach the cooler stuff instead of being something that you can enjoy thoroughly. You wouldn't want to follow a character who's basically a cameraman, would you? Well the childhood portion of the story is where the protagonist is a literal cameraman.

And fifthly; the "tepid" idea presented in the prologue is much more interesting than the childhood portion of the game. Sure, you can like the other one more, but I would rather have a character who goes through an intriguing period of their life instead of a child with very little agency and have just boring slice-of-life childhood sections that nowhere near deserve 350+K words.

Oh and you can add the whole "growing more entrenched in the world" and "building mystery through smaller flashbacks" thing without stealing the entirety of a story as well. That's called good writing. Shoehorning it into the story through an insufferable amount of time isn't that.