Heroic - in any way - stories that relate activity not common to the reader's daily life are called ‘incredible’ - not credible - or ‘mythical’. When life experience provides the needed faith to consider the stories credible, as it does for Christians and the other religious, some of the religious then choose to omit the stories from the term "mythology".
But there is little need for such sensitivity to this label. The use of the term "mythology" to mean not true seems to be ending. Research has shown that much that has been labeled myth has been found plausible, if not provably true (such as in recent under water findings in the Black Sea of Noah's "great flood" and the discover of the physics needed for the "parting of the sea" by Moses, and the finding of the bone box for the priest that condemned Jesus).
So the Bible, the Koran, the Mahabharata, and the thousands of clay tablets from Mesopotamia may tell stories that in the end are not "too incredible to believe".
So there are groups combining ancient megalithic structures, building pyramids at ancient sites all over Earth for a period and then stopping and not building more, gigantic lines and figures (the Peruvian Nazca lines, the Bolivian "ceques", British "ley" lines) on the surface of the earth and "artwork" on Mars(? humans have the ability to see structure where there is none), with the idea that there were ancient astronauts known as "the Gods" who were feed by the vapors emanating from food and drink which humans provided and burned for them. And as God in Heaven meant God moved through the air, we having flying Gods- I didn't say the logic was greater than science fiction by a 15 year old - but hang in there.
Just as some atheists confuse "could have been this way" - as in the possibility that the Bible is just earlier myths being copied by Christians and Jews - as proof that "it did happen this way" - forgetting they are talking about an unknowable topic, these folk look for all the "could have happened this way" - and it is a lot of fun to read!
So we have apes "suddenly" becoming "men" via a mix of Cro-Magnon man with ancient astronauts 10,000 years ago, giving us the emergence of a full-blown intelligent civilization. Don't ask why the ancient astronauts left earth just as we became fairly smart (the “Fermi Paradox” or “Space Travel Argument” used by Freeman Dyson and others to put down the project SETI).
Zecharia Sitchin (see The Cosmic Code: Book VI of the Earth Chronicles by Sitchin and Neil Freer at www.ancientX.com) runs with the above, saying that ancient Sumerian clay tablets reveal that gods from another planet (a 10th planet Nibiru, which orbits our Sun every 3,600 years) arrived on Earth some 450,000 years ago and created humans by genetic engineering of female apes. Sadly, because I like the story, Sitchin says his story hangs on the 10th planet (now discovered) every 3600 years wandering through the inner solar system effecting the Earth, sometimes in catastrophic ways - and that seems a no go!.
But today we may have found a real extra terrestrial beginning to intelligent life on Earth - the Martian Microbe!
http://www.guardian.co.uk/uk_news/story/0,,1989431,00.html Of course this does nor explain how life developed on Mars, now does it?