I had no idea where in Africa geneticists thought 'Y-Chromosomal Adam' was from, but obviously I was pleased to discover this MAP of haplogroups and languages. It includes the recognition of Haplogroup A00, which was first published in 2013. I would call A00 reliable evidence, in contrast to one-time fossils finds, which may be false. More A00 genetic evidence has been independently determined by others since 2013.

This map is especially nice, because it shows languages and is not cluttered up with age estimates.

Old age estimates of A00 in the 2013 article were corrected by competitors in a publication in 2014. This type of correction is not usually possible with fossil interpretations, because competitors are not allowed access to the fossils or fossil locations.

The Khoisan people, who have a high frequency of Haplogroup A2,A3, also have genes that promote a unique amount of blubber (https://en.wikipedia.org/wiki/Steatopygia) which would be of value to aquatic apes, and not especially useful for terrestrial or arboreal ones. 

Khoisan people also have genes for elongated labia (female genitalia) that might have somehow helped women living in water avoid infections. 

Khoisan are thought to have the world's oldest language. It is characterized by click-sounds. Maybe aquatic humans on Bioko spent most of their time singing and click-talking in the water.  

I think chimpanzees became isolated on Proto-Bioko 6 my ago. After only one generation they were probably bipedal and pretty good swimmers. Evolution would go fast due to the extreme aquatic selection pressures. Most babies would likely drown soon after birth, and a new baby, maybe wth more human-like features (such as better nose and more blubber) could be born quickly to the same mother. After 100 generations (2000 years) the semiaquatic Bioko-apes would be so evolved that no one would call them 'chimpanzees'. After a million years, they were probably fully human (semiaquatic.) But we have no fossils of them. And any humans that left the island during the first few million years were quickly killed by predators.

If Khoisan have been on their continent for the past 200,000 years and North Americans have been on their continent for the past 20,000 years, that difference is trivial compared to the 5,000,000 years of humans in the water on Bioko. But Khoisan (in their genes, anatomy, physiology, and language) would be closer to the semiaquatic humans than North Americans are. So in my opinion, no living humans are significantly closer to chimpanzees.