I also agree.
Not only did blacks turn on other blacks and sell them into slavery, there was at one point over 30,000 (I forget the exact number) slave owners in America who were black.
In fact prior to the mid 1600's it wasn't slavery, it was indentured servitude. The difference is under slavery the slave is property of the slave owner. Under indentured servitude the servant is not the property of anyone. They are indentured to pay a debt. In the case of indentured Africans there was no debt they were paying off, so it was still a form of slavery but the land owner did not own the servant. And it was possible for many Africans to work off their servitude and be free. A whole lot of poor Europeans came to America and became indentured servants to pay off the cost of traveling here. Typically when a servant paid off their debt, the land owner would give them a indenture package to help them get started on their own. The most common indenture package was 40 acres, a mule, seeds, food and a small amount of money. This was given to Africans and Europeans both when their time was up.
Now I am under no delusion that all more most Africans stolen from their home lands were free after a set number of years, like the Europeans were. Most of the time Africans were indentured for life. And that type of servitude is almost as evil as the notion that one man can own another. I oppose both.
However, it was a black man and former indentured servant, named Anthony Johnson, who had borrowed an indentured servant (whose name was John Casor) from another land owner. He went to the English court and sued for ownership of the servant. He lost that case but appealed and for some reason the courts, this time, not only ruled in favor of Johnson but they also ruled that one man can own another man under the law. So in 1655, Anthony Johnson became the first actual slave owner in the Colonies.