You realise how hard your request would be due to the lack of writing in the West-African sub-region due to the lack of writing?

But look at this way, by the 11th century Islam had been introduced in Kanem Bornu and quickly spread reaching its apex during the 19th century Jihads. What is Islam's stance on homosexuality?

Away from Islam, a common practice in Western Africa was the betrothal of women, and seeing that a common indicator of wealth was often in addition to the size of your barn, the number of wives you had, we can conclude that heterosexuality was prized and encouraged in the region. Not to mention that more children meant more help in the farm, furthering encouraging a hetero-sexual culture.

Further more, I remember reading in secondary school about Kabaka Nwanga of Buganda being accused of "sodomy". It was used to disparage his character and led to him persecuting his followers, it was one of the remote causes of the civil war that led to his removal.

Heading to North Africa, while the Ancient Egyptians and countries of the Maghrib may have had liberal views, those certainly changed with first Coptic Christianity and later Islam's introduction.

To East Africa, its main empire was Ethopia, Been Christian since the 3rd century, so we can hazard not so accepted.

To Southern Africa, my knowledge about this part of Africa is sketchy.

So conclusion, for a large part of Africa's pre-colonial history, it has been influenced either by Islam or Chrisitianity, in areas where it was not those societies often practiced a system that prized heterosexuality and its "offspring".

But keep in mind that pre-colonial Africa prized ability above all, think of that what you may.