How does this guy learn things? He said initially to Maria "people look after themselves in this village", but that was clearly just him, who decided at 2 "Ok, I'm an adult now, i'm going to go live by myself" and took off with one knife into the woods. No one told him to do that. So he grew up as a wild child, then at some point "became patriotic" and went off to fight in the war as a mercenary for the kingdom. I can maybe understand that he went to fight because there was a conscription, and he thought fighting might help the villagers that had to leave return. But there's no reason to think that "fighting for the kingdom will help my village". And indeed, had he not returned, they would have starved during winter.
Then during his time as a mercenary he taught himself in five years, while also fighting a war and building up a mercenary squad of his own, how to read and write, maths, and accounting. Which ok, those are necessary for running a mercenary company. Then he learned about cattle herding, and the habits of great cows in particular. And how to make cheese and other milk products. And carpentry. And about spiritual arts, magic beasts, and who knows what else.
And despite all this, he never learned that it takes nine months for a human child to grow.
Author, you can't have your MC be both a wild child who is ignorant of human customs and basic facts of biology, and also a knowledge sponge who instantly "civilizes" everything he sees with knowledge he pulls out of his "life as a mercenary", as if that was an excuse for anything you need him to know. All of which he learned in five years.