Funny thing is, I never intended the MC to be a self insert. He has his own strong personality tropes. He comes from a previous game where there's literally a warning saying "do not self-insert".It is about the transformation of the girl. Is it really that hard to get? Well, whatever. You do you man. I was once self-insert harem-assemble type of guy too. Maybe you'll understand once you become older and grew bored with stuff you find hot now.
The purpose of his appearance is to make him "invisible", just a snarky voice commenting about a world he doesn't belong. Relating to him as an outsider and self insertion are not the same thing.
It's a parody. It's more about the original characters not the player character.