I think adding in either a myth about talking humans, or historical evidence for such (how about "cave paintings" or something, written in Vlandi, which the locals can't read, but the players can. maybe a log by the last intelligent colonists as they were hunted down, or the crew of a previous crash landing).
oh, oh, the "Cave" is the remains of the old colony starship, maybe a classic traveller ship like a Far trader (i assume the planet is a backwater or otherwise off the Mains, so a jump 2 or better ship would be needed). the apes know of its location, but can't get in, as they lack the knowledge to get though the locks and such. lengend speaks of the Men of old, who spoke like Ape, and could work wonders. when the players turn up, three steps behind the plot and carrying enough firepower to level a small city, one of the apes points the humans at the " Iron Cave of Men". since players are players, i'm sure they will have no trouble getting in, getting the parts they need and maybe completly upsetting the Apes idea of life as they go.
another cool idea would be having Uplifted dolphins in the seas, which have (for what ever reason) retained knowledge of humanti, but maybe lost how to speak Galanglic.
actually, why not make the apes (and the dolphins) only speak Vlani? the orginal colony was a solomani led effort but the colonists were almost all of vlani stock, and so you get a language barrier (which can be overcome fairly easily, mabye via a com-dot with a vanli translator in it).
