I think it's funny that people act like this whole thing is just some nebulous crusade to cancel things and that we've no idea who "they" will come after next.
Enslavement existed in Africa, but it wasn't racially-motivated like slavery in the U.S. was. In ancient Greece and the Roman Empire, slavery was closer to "indentured servitude" in that it was typically in payment of a debt owed or restitution for a crime committed. In the U.S., human beings owned human beings. These differences don't justify any sort of slavery, but to pretend we don't know what people are so upset about is ridiculous. American chattel slavery is a unique evil that we have not healed from. In the U.S., human beings owned human beings (and their children), and rationalized it by saying that black people were inferior.
The efforts we're seeing now is to root out the influences that cause, reinforce, perpetuate, and excuse the philosophies, attitudes, and policies that allowed such an evil to occur in this country.