I forget who said it, but one theory I've heard is that kids are naturally afraid of their parents and haven't built the ability to hold opposing views at the s

I forget who said it, but one theory I've heard is that kids are naturally afraid of their parents and haven't built the ability to hold opposing views at the same time, so they have trouble reconciling these loving god-like figures they depend on 100% for survival and the total fear they have when the same figures are angry or disappointed in them. Stories like Sleeping Beauty or ones with monsters allow kids to transfer those feelings of all encompassing fear to these bad guys, until they outgrow it and they're able to handle ambiguity. That doesn't explain why the stories were originally told, but could explain their stickiness.