To some extent that is true. All groups of modern humans have some DNA from different recently extinct non-homo sapiens. West africans and bantu in particular may have some admixture from at least one primitive homonin that would have branched off from the family tree several million years before neanderthals (~4.5 million ya, see MUC7 gene, Xu - 2018). There is an increasing amount of evidence that the Khoisan and central african pygmy populations are the people most properly thought of as indigenous sub-saharans. They branched off from everyone else around 70,000 years before other blacks (west africans/bantu, east africans) did, which is around the time australoids branched off. These later blacks (99% of black africans today) may not have moved in to subsaharan africa until 3000 years ago or so. Where were they prior to that? Possibly a less arid Sahara, possibly the middle east or southern asia. West Africans have a large amount of introgression from archaic homonins. Up to 18% in some individuals according to one study. Its not clear when they picked it up or if they picked it up directly or through mating with pygmy populations or whether there were several major introgression events with multiple species. A lot of answers are needed pertaining to the origin of west african/bantu and east africans. The more I study it the more it seems to me that a very sizeable chunk of their ancestry (>50%) is not particularly african. New questions keep arising from genetic studies. It may be that most blacks today are descended from some basal eurasian population that back migrated and mixed with some really primitive homo erectus types and pygmies and then some much more recent eurasian migrations were added. And then they moved south out of northern africa and genocided the pygmies and khoisan.