Unless you want to make an argument that any omni-whatever being is, by definition, alien. But that's not the same thing as extra-terrestrial aliens.
It's certain that out there, in the umpteen trillion trillion stars out there in the universe, we can't possibly be the only form of life. But, even being generous with the numbers, the odds of there being a living creature within ten thousand lightyears of earth that isn't actually a *native* of earth is pretty much nonexistent. And, assuming there is, it's pretty well a 50/50 chance that it'll be found in our solar system (europa has a chance, at least, of something alive- and mars might well have frozen critters for us to prod at).
But full blown sapient beings. No. Not in our solar system. We're the extent of it. And there's a solid chance we might be uniquely intelligent... at least in this arm of the galaxy.
Chances are actually better than ancient man possessed full blown fantasy magical sorcery than that ancient man has met with extra-terrestrials. And time travel (of the entirely human-curiosity type) is more probable than both combined. And chances are pretty good that ancient humans were just a whooole lot more intelligent, clever, and physically capable than we give them credit for.
Humans haven't been getting smarter- we've collected more knowledge, but we haven't actually improved our brain's ability to make leaps of logic and intuition or store information. But we HAVE been getting a *lot* weaker, more dependent on equipment than on our own bodies. I would not be surprised to learn that the people of a thousand years ago could pound the living crap out of any modern man, no matter what athletic accomplishments they think they possess.
Mind you, that's a lifestyle thing. We modern humans haven't used our bodies to their fullest potential in a loooong time. So long that, as a culture, we've actually forgotten how. But there's no reason that you or I couldn't do everything a person on a PCP high can do. Drugs don't break the laws of physics OR biology- our muscles ARE strong enough to bend steel. Our bones able to take five story falls. And our bodies can withstand bullet fire.
If ancient man knew how to push their bodies to the biological limit (just like every animal on earth other than humans can do)... well... stonehenge and the pyramids are suddenly very achievable.
Also: don't do something stupid like mention the mayan calender. There's nothing alien about that. Brilliant, sure, but entirely human achievement.
I'm honestly far more impressed by the bible. Leviticus. If you pay attention when reading that- those laws were written by someone who understood disease in ways that modern science didn't figure out until after World War 1.