Spot on.
Sahelian West Africans are clearly the most obvious groups that African Americans are descended from. From Kunta Kinte to rice to cotton crops to the Blues to Islam in the USA; it is obvious that African Americans are largely descended from the ethnic groups in that region.
The high Ivory Coast/Ghana test scores on the Ancestry DNA testing is no surprise when it comes to African Americans, because the English leaned heavily on getting people from the "Rice Coast", which are the areas largely from modern day Senegal to Liberia. Many people from the Rice Coast were taken largely to the USA states of Georgia, South Carolina and North Carolina. The people were shipped largely from Bunce Island in Sierra Leone and Goree Island in Senegal.
Fwiw, AncestryDNA.com doesn't test for Guinea, Sierra Leone, Liberia, Burkina Faso, Mauritania or Guinea-Bissau so Ivory Coast/Ghana, Senegal, Mali and Togo/Benin acts as a proxy in those tests for many Sahelian groups. The interesting part is that a lot of African Americans ancestors ended up in slavery due in large part to the decline of the Kingdom of Mali. After that decline many Mande groups moved West into countries like Sierra Leone and Liberia in something called the Mane Invasion (Mande Invasion). A couple of centuries later it was those Mande people that English coveted and paid a high price for, because those groups were highly skilled in the growing of many crops; in handling livestock and in the trades. Of course later on the English found out that those people were highly skilled in music and in the other arts, which is how the banjo, blues and gospel music got to the USA; as well as dishes like jambalya, hopping john, etc., which are offshoots of Jollof Rice.
It didn't seem to matter to the English that most of war prisoners that they purchased to slaves (Mandingos, Mende, etc.) were heavily Muslim; which so many people from that area ended up in the USA and in Anglo Caribbean controlled Islands rather than in Spanish and Portuguese controlled regions.
Incredibly interesting region.
http://www.webmande.net/bibliotheque/massing/mane_mali_decline_mandinka_expansion.pdf
The Gullah: Rice, Slavery, and the Sierra Leone-American Connection | The Gilder Lehrman Center for the Study of Slavery, Resistance, and Abolition