Because They’re There.
Maybe the weirdness of humans isn’t in our squishiness or our resilience or our strange cultural quirks. Maybe the overriding ‘alienness’ of humans when compared to other species is our undying curiosity and drive to go further when we don’t need to. Other aliens explore and expand when it is required. There is no more space here so we must find more there. But humans will go out and explore an ocean just to see what’s there.
Zing (not their real name, but they were adapting to it as the only one the majority of their crewmates were able to pronounce) trudged into the communal area of the hive. Sub-Hive 9hXGsse was unimaginatively named and unimaginatively staffed and unimaginatively run. Often referred to as the loneliest system in space it was mainly manned and suited for outcasts of various species.