"what part of africa is most likely to hold the origins of jazz and is the homeland of most africans who were brought to the americas as slaves? "

Western Africa.

Explanation:

Blues and jazz are influenced by African rhythms brought through the transatlantic slave trade that took slaves mostly from central and western Africa to be bought by European slave traders and sent to the New World. Gospel music, the African-based rhythm that later developed into jazz, had its roots in the call and response practiced in the slaves´ spirituals.