Before the religious adoption of Christianity and Islam by many Africans, there have been religions in Africa

Religion everywhere is a product of CULTURE (the ideas, customs, and social behaviour of a particular people or society).

In ancient time, African ancestors were polytheist of numerous deities while the modern-day Africans monotheistic belief in one ‘Supreme Being’ was a latter claim in rivalry of the ‘Almighty God’ of Abrahamic religions... The ancient African establishment of religions in the diversity of deities began when ‘power and influence’ questions the Native Leadership of African People. 

African deities are numerous, so are the African people populous, and practically all ancient African native family compounds, communities, districts, villages, towns and regions — diversely worships different deities. So, individual deity worship, then becomes individual religion, followed by inter-religious rivalry... and from that moment onward, an African child's ‘religion of birth’ and language becomes his/her first form of identity before any other cultural values. 

Till date in Africa, there are millions of shrines anciently attributed to numerous deities, and all the shrines practice their religions diversely with different religious doctrines & customs.