I’m not trying to minimize anyones life experience with my previous statement. We try to improve society as time moves forward, and if we are successful at that, that means that in the past things weren’t as good/inclusive/knowledgeable as they are now. Public knowledge on sex/gender/biology has advanced a lot since we started using the terms straight gay and bi, I was merely acknowledging the past existed as it was, and that they worked for the more limited public knowledge that we had then, we know more now and they’ve become less relevant/useful because of that. The one thing you are wrong about though is yes, it WAS primarily about genitals, if you had a dick and liked dick, you were gay, same with if you had a vag and liked vag. If you liked both, it was bi, and if you liked the opposite it was straight. Society as a whole didnt fully understand the difference between sex and gender then though, so what genitals you were interested in and what gender you were interested in were used interchangeably, but that didnt stop the primary purpose as it was generally understood back then from being specifically which sexual organs you wanted to do the nasty with.

Tl:dr: as we advance our understanding of our world and old models become inefficient/outdated, it doesnt mean they werent compatable with our modern understanding of the world out of malice, it just means we have advanced to the point they no longer work