In fairness, the roles were all written as unisex roles with no specific gender in mind. I’m pretty sure they didn’t have three sequels in mind when they were writing the original script…
I’m just saying if that was the original intention it would have been a lot more impactful with a male lead for the audience to attach a common fear with as they struggle to avoid the proverbial rape situation and completely avoid the issue brought up in the sequels. Not to take anything away from the cultural phenomenon that the original Alien was for having a strong female lead.