A lot of people believed or were forced to believe slaves were the lowest class and slavery was natural and good for them. They were believed to not be capable of being a part of society. Because they were not believed to be capable, they were not taught to read or write. They were basically believed to be lower than animals, so in most cases, they were treated like or worse than animals.
Because Ham looked on his father Abraham's naked body, he was forced to be a slave to his brothers. He was also cursed. God said that him and all of his descendants would have a hard life and be enslaved. People were often named for physical and/or emotional qualities then. Since Ham means 'dark' or 'black', I guess you could say that God cursed black people. (that comes out really straightforward and a bit angry, but i couldn't find another way to put it.)