Realistically, if we encounter Sapient Alien life forms. It's more than likely by that time that the Male Sex would have disspaeared. The Y chromosome is already shrinking and by the time that we encounter aliens, I imagine it would confuse the heck out of them.
Alien: So Human Beings only have one sex?
Alien: But... But you reproduce sexually?
Human[is fed up because this is the 32nd alien): Also correct
Human: Welp, the Y chromosome started shrinking but due to the patriarchy this was considered illogical as it was considered the superior sex.
Human: I know right? I don't get it either but apparently that's what the Thesis I read summarised. -Anyway, by the time we realised it was a legitimate concern we had climate distaters, collapsing ecosystems and a few pandemics so it wasn't high on the priority.
Alien: So you faced Extinction? And ... Survived?
Human: Well by that time we also already had the technology to reproduce sexually without the need of the male sex. So it wasn't really extinction more a vestigial trait that technology had already made redundant.
Alien: ... Let me summarise. You advanced technologically and your species evelutioanry genetics responded by removing the redundant sex? You extincted half of the humans because they became useless?
Human: I mean, it wasn't intentional but I guess so.
Humans are known as the most ruthlessly practical Species to ever traverse the stars. Surviving shock because it's necessary. Tapping into all their strength and injuring themselves for the young and the greater good. And more, weeding out their own population when vestigial traits proved impractical.