Have you ever seen the movie Epic? With the little forest people? Imagine a world where they exist, and write it out. You could be one of them, you could be an animal, you could be a child that stumbles upon these creatures, or you could just narrate.
I'm not asking for fanfiction, but you could do that if you want to. Just know that I don't like the movie that much.
Anything goes, as long as we keep it at or below pg-13.