What if we come from a space traveling civilization, and we indeed used to be able to make contact with them (ancient ancient civilizations). But something happened to our actual home land thousands (or millions?) of years ago, causing the home world and our race to go extinct. Causing us to forget where we actually came from, yearning to get home. That's why all of us are so drawn to space, because earth isn't our home.
Also, what if the "greys" or other humanoid space species, are actually just another version of our original selves? They may have had other colonies besides us, and they're trying to make us whole again
I agree, we probably evolved so differently on that planet (we were probably more involved with water, probably lived in it) and that's why we have had such a desire to build all of our cities near it (besides the fact that we drink it), and praise it in so many ways. Our ancestors must have mated with the different species of early hominid when they arrived.
That's why were so different to almost everything on earth because were a bit of terrestrial being, with some extraterrestrial being
All of the evidence points to human beings having evolved on Earth. This 'lost colony' stuff is a bullshit disinformation campaign being spread by an Alien star empire so that when they show up we'll accept being made part of it instead of seeking out and forming an alliance with the true other half of our souls.
Every generation there are more humans, haven't you wondered where all those extra souls are coming from? The answer to the question "Who are you?" is the most interesting one.