The statements presented here are my straw-men, meant to be attacked and dismembered.  I hope to then reassemble the remaining pieces into a stronger whole.  Please feel free to offer constructive critiques and your own suggestions.  My goal is to focus on the most straightforward and plausible possibilities   However, that does not mean conventional world views will be given an advantage.  This ideas must stand on their own merits after vigorous and careful scrutiny.

1. The simple mechanistic view of the brain and consciousness are fundamentally incomplete.
2. Some people have a different level of perception that seems to tap into other ways of knowing.
3. Time is more complex than the simple linear increments we usually count based on local observations.
4. Not all lights in the sky are conventional technology or weather events.
5. Sentience in the galaxy/universe/space is not limited to our Solar system.
6. Sentience on Earth is not limited to humans.
7. A number of different hominid groups have developed sophisticated civilizations in the past.
8. Major civilizations have risen and fallen in a number of catastrophic cycles earlier than 5,000 years ago.
9. Modern humans did not triumph due to more brains and innovation,  I suspect we interbred and procreated our way to dominance.  It appears to be what we do best as a species.  (Humans will breed with anything.  Everyone else has standards.)
   1. Consider shorter gestation, more frequent fertility, longer lived or longer fertile period?
10. Elders will tend to tell the truth as they see it to their own decedents and community.  Most people seem to want to leave a legacy of adding real value, not just telling great stories.
11. Oral tradition is a substantial source of subjective experience.   Oral traditions and folk lore should be treated as usually inspired by actual events.  If a people considered a tale as important enough to remember and pass down, it would likely contain very important information.
12. Virus interaction with hominid DNA may have resulted in sudden jumps in evolution.  Perhaps viruses have been one of the major drivers in evolution.
13. Any advanced alien race aware of our presence would,
    1. first send probes and scouts.
    2. Explorers and privateers might come next.
    3. Then scientists and missionaries.
    4. Then conquest and assimilation.
    5. Then autonomy and diplomacy (if we are lucky).
14. Space travel would not be a huge barrier to robotic, AI or disposable cloned pawns.
15. A species with a very long lifespan would not consider space travel to be prohibitive.
16. One way colony/explorer star-travelers, who could sail at close to the speed of light would not be deterred by the time gap to their home world, since they would not be returning home (even if their planet of origin even exists any longer).
17. If a far advanced civilization wanted to genetically modify us as a population, they would release tailored viruses not abduct individuals.  Therefore, abduction must have another purpose.