Could there be lost humans walking around and being brought up living on alien planets?
A bit like peter from guardians of the galaxy or doctor who where you see some humans around millions billions or trillions of miles away living like normal on another planet. If they were picked up or abducted, there would be absolutely no way of knowing if they did, humans probably wouldn't know and could be wiped of their memory of Earth and walking living and breathing on other planets. What's to say there aren't billions of other planets out there that are habitable for humans??