Yes you are much more on point than anyone else so far in the thread. To sum it up very basically.. There are 3 main genetic linguistic and ethnic source populations in Africa. West African/Bantu. Nilotes. And Afroasiatics.
Bantu are a sub group of west Africans who in the Bantu expansion spread to most of Africa. They are the "typical" African most of the world recognises. Most of west Africa, central and south as well as parts of east. I think they are genetically best at sprinting.
Nilo Saharans are from the Nile valley only in east Africa. They include kalenjin who are about 80% of Kenyan runners. Typical ectomorph Kenyan runner body type.
Afroasiatics in Africa are generally mixed between indigenous Ethiopians/proto Nilotes and middle eastern to varying degrees. Ethiopians, Somali, Eritreans.
Some Bantu and Nilotic admixture is present in Kenya, as well as some some Afroasiatics (already mixed middle eastern and Ethiopian) and Nilotic admixture in both Kenya and Ethiopia.
I really think the sprinting in Kenya comes from Bantu genes. Nilotes are built for distance running and mixing with asiatics seems to have little effect on their ability because they also have quite a gracile build and retained the adaptions for living at altitude.