You think Mother Goose is scary!? Well, she is, and the Grimm fairy tales are beyond Grimm. They don’t tiptoe around evil and are not sugar coated. Disney has to do some serious cutting to make fairy tales into movies.
The lines which instantly come to mind are
Here comes a candle to light you to bed
Here comes a chopper to chop off your head
I know that "Ring around the Rosy" was written about the plague...back in high school, in an EngLit class, we had a few classes about children's lit through the years. It's always been on the bloody side, that's not a recent phenomenon.