But I don't believe we were civilized by aliens, that notion is absurd. We evolved and created tools, and farming, technology evolved as we did, a little understanding, the next step etc.
But it is possible that they have visited earth since if they were from the edge of the galaxy, their planet would have existed for billions more years, they may have figured out a way past light speed, immortality etc.
I think the days of 'star trek' and 'alien' where we're all floating in space going to other planets is probably 100,000 years away. thats an arbitrary guess, but we don't have the resources or technology to make that type of shit viable for a long time, and get to planets we could make money off.
Yet college physicists demonstrated quantum locking at a trade show in october and a medication for progeria is going to market in the next two years.