African Americans are going to be from almost every African ethnic group there is. There were Civil wars and slave raids on the continent for hundreds of years. The losers went into slavery and were sold to the White man or the Arabs. I don't know where people ancestors are from but DNA tests would show people the modern ethnic groups that their ancestors descended from.
By the way I knew nothing about the Kaba people and for that matter the Bulala people until I took a DNA test. The Bulala are also from Chad. They sacked Kanem and forced that empire further west to Bornu (Nigeria). The Bulala in turn set up a trading empire; where they were the middlemen between Egypt and Sub Saharan Africans.
Bilala people - Wikipedia, the free encyclopedia
Just so people have an idea of where Chad is; it is right next to Cameroon and Nigeria. The whole region was raided for slaves.
Saying AAs descend from almost every group in Africa is a big statement and its on you to prove that. Btw most slaves from Chad if I remember correctly were apart of the Arab slave trade and went east.
Anyways a much better and simpler argument would be to say African-Americans and their ancestors share affinities with the Ancient Egyptians going back to the Wet Sahara. Or better yet there are groups in West, Central and even southern Africa who claim through oral tradition that they migrated from the Nile Valley or Misri(Egypt). I mean the Dogon people are said to have migrated from Egypt and their religion, gods and traditions are quite similar to those found in Ancient Egypt. But do AAs even largely descent from the Dogon is the bigger question...