Questions about American history that need public answers

The history of legalized human trafficking in America is a story that should be widely known and told:

How did it start? What was taught to attempt to justify it and to keep it going? What was it like for its victims and its perpetrators? Why did it last so long? How could such oppression be embraced by a society that treasured liberty? Who were the courageous people who openly opposed it? Why weren’t there more of them? Why are its perpetrators honored while the abolitionists who spoke out against it are forgotten (or even villainized)? Why did so many American churches support and embrace such cruelty?