This is a quick note (on my way to writing a much longer post) that kids aren’t idiots. Many of them are quite smart. The readers, obviously. Maybe you are a kid (or were once one) and since you are on this site you are quite smart. My daughter is very smart and she’s only ten, although she seems to get older every year.
So why, in so much young adult fantasy and science fiction are kids idiots. Harry Potter makes so many bad choices. Sure, Hermione gives good advice, but she also spends a lot of her time plagiarizing papers for various Gryffindor house members. Lucy, Ged, and Meg Murray didn’t make idiotic mistakes. They made human mistakes. Arthur was driven by his urges and made those mistakes. I feel adult writers now think too little of younger readers and younger protagonists.