In terms of Western TFs, Airazor was the first official Female Transformers character toy that was mass-released (Nightracer was the first, but was a BotCon toy).
And only the head of Minerva was technically female, as we never saw what the robot's gender was after the kids were separated from them.
(but at that time, I think Hasbro would have been taking the lead on toys & characters, so Nightbeat's "masculine" form would have been the original form)