Slavery didn't really end a hundred years ago after the US civil war. Elements of slavery persisted, including the skin color-based caste system which still exists today. Even in recent history, there were instances of racial discrimination like segregation and mistreatment of Black individuals. This caste system continues to influence people's beliefs. While it may seem backward, it is rooted in the past where the Middle Ages shaped people's thinking.
The Atlantic Slave Trade mixes centuries of human bondage with violence, economics, commerce, geo-political competition, liberty, morality, injustice, revolution, tragedy and bloody reckonings. That sounds like a lot, yet this show merely scratches the surface of this enormous subject.