I thought that the idea was really good, and the music itself was fairly good as well. I can't say too much about the animation, as I know next to nothing about it, but it was fine. I think, however, you could have picked the songs more carefully. Humpty Dumpty I can understand, and 5 little ducks up to a point, but for the second and third songs... what you had animated wasn't even implied in the songs. You could have picked ones that actually have the implied violence/gore/whatever. Ring around the Rosie, for example is apparently about the Black Plague. You could have had multitudes of people dying there if you wanted. Rock-a-bye baby falls out of a tree, Little Baby Bunting gets wrapped in a rabbit skin, that kind of thing.
Again, great idea, but you could have picked better nursery rhymes for your animation.