Elephants and rhinoceros may have aquatic ancestors but that does not prove that humans did. We (presumably) have fossils of aquatic elephants and rhinoceros, but there are no ancient aquatic hominids. If there were ancient aquatic hominids then we could start theorizing about what adaptations we acquired in an aquatic niche (and then a terrestrial niche). But if we make up the adaptations first, assuming that an aquatic ancestor existed, then we are just creating a fictitious evolutionary tale. Furthermore, anthropologists already have well-developed theories for why humans lost their hair, became bipedal, developed large brains, etc. These theories have been tested and match the empirical evidence in the fossil record - unlike the aquatic ape hypothesis.
You've never heard of the swamp ape, Oreopithecus bambolii?????? Marcel F. Williams