Some creativity advice involves "getting in touch with your inner child." It's the idea is that children are more creative than adults. Is this true?
Ellen Winner reports in her book Invented Worlds that before preschool years, children are quite creative with similies. They might say something like "quiet as a magic marker." But after the preschool years, they start using conventional similies, such as "quiet as a mouse." Interestingly, this is when school starts, and when kids start getting interested in social rules, both ones they create (in games with other children) as well as as the rules of the adult world. Middle childhood is characterized by a fierce conventionalism—they might object to a female wearing male clothing even more than an adult would. It's only with age that they loosen up about rules and see nuance.
Early childhood is when we see the most creative "pretend play," in which children actively create their own imaginary worlds. These games, if you even want to call them that, can involve other people in a shared imagined experience, but are often non-competitive. After age five, though, they start getting interested in games with rules, and you'll see them argue about the rules and who is or is not following them.
If you're getting in touch with your inner child, make sure your inner child is young enough.
Winner, E. (1982). Invented worlds: The psychology of the arts. Cambridge, MA: Harvard University Press.