What are stories?
It's hard to get behind this question because we are always inside it. We are in stories (narratives), we make them up, we use them, we are in some senses made by them. It's very hard to think, talk or write for very long without starting to put things into a sequence that relates something, retells something.
In a way, trying to figure out what they're for is a bit like meaning-of-life and what-makes-us-human questions: too big. And yet...there ought to be some way to distinguish 'storying' from other things.