I found it interesting that the witnesses insists on calling it “non-human”, but never directly refer to them as aliens or that they even have an origin beyond our planet.
I always felt if the little green/gray men were real, that they are not the real aliens. I imagine they would be more like drones or androids that may even be some sort of advanced AI, which would make the whole how can they crash if they have the technology to reach earth make more sense if there is a chance they can malfunction. Perhaps they don’t travel from space to here anymore, only did it once, and have a base of operations underwater that is like a warehouse to create more android pilots to do whatever it is they do in our airspace.
I’m just imagining here, but the truth is aliens may look humanoid, but they may not. I think the public seeing them look more humanoid would be easier to process than if we see that they look like a breathing ovarian cyst.