Being that our galaxy is ~100,000 light years in diameter and ~1,000 light years thick, it
is pretty inconceivable that humanity will ever travel across the entire thing, let alone
other galaxies. Unless we discover faster-than-light travel, or some sort of infinite
improbability drive. Heck, the time spent just traveling to nearby stars is long enough to
make it just a one way trip.
As for ancient astronauts, there is no way for us to know for certain. I have seen UFO's 3
different times in 3 different places, so I don't discount the possibility of other
civilizations existing. It's just that there is no solid evidence for it. There are
hallucinogenic plants all over the world that could make anyone think that they are seeing
beings descending from the sky, especially in the minds of people who had less knowledge
and understanding of the natural world. That is a more plausible explanation for any of this.
In all honesty though, how could you not believe everything this man has to say...
Just look at that hair.
And, he's even wearing an ancient flying machine on his jacket.