Since I can't seem to comment on the other thread, I'll do it here. - In Mass Effect 2, they deal with why the Asari look human, in one of the conversations on Ilium, after several characters of different species argue over what species they more closely resemble, they come to a horrifying realization that the Asari control their minds to make them appear more attractive. So the reason they look human is because we (the observers) are humans, to a krogan they're krogan, to a salarian… well you get the idea. As to why almost everything else is humanoid, well that's a different trope.

Does this trope have a fantasy counterpart?