Why are the motifs in so many english language nursery rhymes dark or having to do with violence?

by CheeseVikings

Bridges falling , death from the plague , babies falling from trees?

Searocksandtrees
CJGibson

The notion that Ring Around the Rosie is about the plague was apparently entirely made up after the fact. The wikipedia page has more.

The page does reference "interpreters before the Second World War" and how they don't mention the plague. I'd love to know what they thought the rhyme was about, since wikipedia doesn't seem to explain that at all.