The island is strictly pre-teen, with no messy hormones to make things even worse. Maybe some of the boys have peach fuzz—we bet Jack does—but in general, these are little boys playing little boy games. Only the games aren't so innocent. Lord of the Flies asks a crucial question: are kids really innocent, or do even six-year-olds have the beast inside? On the one hand, it's hard to say—we only get to know the biguns, so it's possible that the six-year-olds are still innocent. On the other hand, everyone eats the pig, and everyone helps kill Simon. It's not looking good for human nature.
In Lord of the Flies, children are just as savage and bestial as adults.
Golding suggests that very young children are still innocent, until society and civilization corrupt them.