I know this is generic af, but this is exactly the kind of average series that I really like, no need to think too hard about the plot
Also, I agree that he should've known about certain things like money and schools if he came from another world, but I'll let it slide since it's been 15 years since he was reincarnated, and it has been proven that kids under 3 don't retain much of their memories when they grow up.
But that doesn't really go along with the fact that he knows about stuff like oxygen and hydrogen (in a world where nobody knows anything about science) to create what looks like a nuclear fusion reaction using magic. And even his teleportation spell is known to have come from anime and novels from his previous life.
But then again, like I said, no need to think too hard about it, I'll just choose later on who the best girl is, since they've shown who the main girl will be