They were all members of a free Negro class that, while not having the power of some whites, had been brought up to believe that they were rulers waiting in the wings. They were much better than the majority of white people, and it was only a matter of time before those white people came to realize that.
I didn't think Southern whites at the time had given any blacks the freedom to believe that they were better in any way. The way this is written, it implies that the whites didn't grant this freedom, that it was one the free blacks claimed for themselves. But when a free black man can have his papers destroyed and be sold into slavery at the whim of a white man, it must be hard to develop a sense of being better. Morally better, certainly, but not socially "better." I would think that would be hard.
In some ways, I'm impressed by these people, that they could develop a sense of themselves that goes against everything said by the people with the most power. But I'm also disappointed in them that they still think someone needs to be better than someone else. They are just inverting the dynamic, not changing it.