BECAUSE, the black sheep (black man) is different and is mocked by all the whites for being dark, it is extremely racist and is actually sung at many KKK meetings around the world
No one really knows, and there are a couple of versions. Under author it is listed as tradition, published in c. 1744. It was written in England. Still, it is interesting to look at the history...
Baa Baa black sheep have you any wool? Yes sir, yes sir, 3 bags full. One for my master, one for the Dame, one for the little boy who lives down the lane. Baa Baa black sheep have you any wool? Yes...
No he wasn't racist, because he was giving away some of his wool to the master who was also black, and to the dame who's white. He was also giving his very last bag full to the little boy who lived...