Mmmwell. While ancient sources may or may not be accurate, I see little reason to believe they are more or less fanciful than, say, Star Wars or Asimov's books. There was as much curiosity and speculation then about the unknown as now. Wether that is 'proof'... not really. It was mixed with the science of the day, to be sure, but so is modern hard sci-fi. There is speculation - how could the egyptian pyramids be built so accurately, especially some of the sarcophagi - but it is allready known that a lot that was known has been lost; technology is not a one-way progress, there are setbacks and dark ages.
I would feel awfully alone if there WERE no life out there, somewhere; that alone is not reason to believe there is. However, statistics - another fanciful source, to be sure - suggest there must be. I doubt they have visited; I strongly doubt they are watching us, and I do not think it at all likely that we will see any proof of them during our lifetimes, however long they may - or may not - be. (This, also, is due to statistics.).
Then again, I find the Seti program .. interesting. First, they went looking for the possibility of life on other planets, and calling out to anyone out there. This was because they might find someone.
Then they stopped calling out to anyone out there. This, too, may be because they might find someone.
Encounters with more advanced peoples, at least in human history, has seldom been advantageous for the less advanced one.
