The T-800 is neither male nor female, despite outward appearances. And Sarah was still the main hero in that story.
Correct.
The terminator is a machine designed to mimic a human male, that does not make it either human or male.
Likewise when it adopts Sarahs' mothers' voice it doesn't suddenly become a human female merely by virtue of mimicking one.
The T-1000 likewise "gender swaps" throughout T2, which in no way detracts from the fact that it is a sexless machine.