Any of various small arboreal marsupials of the family Phalangeridae, of Australia and adjacent islands, having a long tail and dense woolly fur and including the cuscus and the flying phalanger.
Only when these hominids had to travel between arboreal habitats would they find themselves walking bipedally, 'forced' to do so by their own anatomies.
This arboreal creature would've developed longer digits and a membrane between them as part of its gliding phase, eventually transitioning into powered flight.