In the Bioko model, all Homo species (including Homo erectus, H. denisovan, H. neanderthalensis, and H. sapiens) were paleohumans that evolved fro chimpanzees (Pan troglodytes) that had become trapped on Bioko.
You can think of these Homo species as different ethnic groups, living at somewhat different times. They were not really different species, because they were able to produce fertile offspring. If you met one of these paleohumans naked on the beach, you would probably not notice that they were anything other than modern humans — until you watched how they behaved and related to each other.
Homo sapiens were probably more modern: more civilized, socialized, and linguistically advanced than the other paleohumans. Language and cooperative culture were developing mostly within the dense population of paleohumans on Bioko. Paleohumans that stayed there longer were better educated than those who left earlier. When people left and lived in harsher places for thousands of years, they became stronger and fiercer, and even invented weapons. But they lived in small groups that were not in contact with others.
Waves of well organized Homo sapiens left Bioko in the ‘Recent-Out-Of-Africa’ emigrations between about 70,000 and 50,000 years ago. They probably migrated along the African coast to the Mediterranean Sea, where they met Neanderthals who had migrated earlier. That coastline is now submerged, so we have little evidence of the presence or coexistence of these marine paleohumans.
The two populations mixed a bit, but the Neanderthals were weaker linguistically and socially and were vastly outnumbered by the Sapiens. Ethnic Neanderthals died out, leaving only some of their genes in the ethnic Sapiens that eventually became hunter-gatherers, pastoralists, and agriculturalists in Eurasia.