I think human ancestors lost their arboreal habitat in exactly the same way that Galapagos iguanas did. They are called 'marine iguanas', not 'aquatic iguanas'. So I will stop using the term 'aquatic apes' and start referring to our aquatic ancestors as 'marine apes,' which became 'marine humans'.
Rivers and lakes could not have been the environment of our aquatic human ancestors. There is not enough food in rivers and lakes, because fish are too difficult for apes to catch. Lake-and-river food does not have enough omega-3 and iodine for brain evolution. Lakes and rivers would not provide reproductive isolation from other apes. Lakes are not geologically stable over millions of years — they either fill up with sediment or dry up at times. And there are too many crocodiles and large predators patrolling lakes and rivers.
I think our ancestors must have been marine.