Why is every character in this novel behaving like a ten year old?

I understand why this novel has the tag "dense protagonist". Every character in the novel makes a real effort to make the protagonist as dense as possible. The protagonist does his best in asking questions and not even 50 % of those questions gets an answer, the methodology the characters use to teach the protagonist are awful. The other characters go "Didn't he know that?" or "How can he not know that?". They are his f**king educators, they are the reason he doesn't know sh*t... All the chapters I've read so far is about educating and training the protagonist and so far all the other characters have done a piss poor job...

I like the premise of the story, the story telling is ok, but the characters are a let down, the author used the same mold for every character. All male characters behave the same, as ten year old little boys, the female characters all behave the same, they are abusive and solve everything with violence. "Oh, you saw me naked by accident?", violence, "You said something that I don't agree with?", violence.

Sure, you can use this template from Japanese novels now and then for comedic relief, but it gets really old when you do so every time and for every character in the novel.