So...
His dad died when he was "little"
His mom died when he was TWELVE so he absolutely had some chance to grow after the age of 12, even if his mama gave him stupid pills every day with a bowl of dumbshits for breakfast.
So, he goes out to the "adventure guild school" or whatever, and while there (and this is important)
HE TALKED TO AT LEAST ONE PERSON ON THE ENTIRE PLANET
In the space between 12 and whatever age he is now (presumably 13), he has spoken to at least ONE single human in his life.
We've seem him speak to some people, while working, but at some point he actually spoke to authority figures in this "Guild" thingy.
So.
He KNOWS, in the first chapter, what the armour of the Empire looks like!
So he knows she isn't a maid.
He knows that the "Buffalo" was called a Minotaur.
He knows it is an S-rank.
He knows that he should refuse any gift (because: Japan, even though literally the rest of the planet earth isn't like that, so why the fuck would any body else do that useless shit?), and then take the final reward.
He knows how not to speak to nobility, even if he doesn't know how to say "Thank you, sir" (see how hard that is? Saying "sir" at the end? It's so difficult.)
But somehow, he suddenly doesn’t know these things.
My only guess is that the person writing this thinks that YOU, the person reading this, is a fucking retard.
This writer thinks you're a dumb fucking idiot who can't even walk and breathe at the same time, because you are just So FUCKING STUPID.
And that feels pretty insulting, honestly; makes it hard to enjoy the story when the writer keeps assuming I'm fucking dumb, and throws it in my face over and over.