the worst insult you can throw at somebody today is “you’re a child”. because in the minds of the US citizen, the child is the worst things in existence. schools exist to quarantine them, to remove them from society, to make them “proper” humans, adults, in other words.
the reason why the child is considered the most despicable object in US mainstream culture is because the child represents nature, the thing that is a direct offspring of biology, instinct, and whatever we consider “uncultured uncivilized being”. in the US, the child is like a piece of dirt, or clay maybe, that has to be sculpted and burned into porcellaine before it’s considered worth anything. even more, the child - through its playful instinct and lust for life - might even represent the animal instinct that has been so successfully repressed in every Grown-up human. and we cannot accept what was never accepted about ourselves.
An adult being called a child is only an insult because people are supposed to gain some maturity as adults. Do most think a child is bad because they cry when they get told no? No, because that’s part of being a child - they have to learn. If you do that same thing at 20, it’s a different deal. It’s not that children are bad, it’s that you should grow out of some things when you’re older. In fact, sometimes people refer to a person as “child-like” as a compliment, but would use “childish” as an insult. Children are prioritized in the US pretty highly.