There are theories of ancient cultures which might have been visited by aliens. Most of them have been proven wrong but the I like the idea and want to set up such a culture which has been visited.
There are many ancient buildings of civilizations which suggests a knowledge about stars that they, as far es we know, weren't able to gather themselves.
Stonehenge, one of the oldest man-made structures at all and a very accurate observatory. The Stonehenge shows formations in the sky which we can not see with bare eyes. How where they able to build this, if they couldn't see what it's pointing to? Maybe by accident, maybe by supervision of a species which could.
Nasca-Lines Giant paintings on the desert which one cannot see from the ground or hills, only from the Sky (Planes, ...).
In the end the theory of pre-astronautic is a wild one with very view references but many speculations.
The Setting is ~ 8 000 b.C. on a fictional area of the earth. The people of this folk are ~ 10 tribes of 100-500 people each which have merged a view generations ago due social improvement, no war, epidemic or something, it's peaceful.
My culture just handled to make fire very hot (~800°C) and noticed that some of these stones "melt" and can be formed then, so they are about to learn how to make tools and weapons of metal. Their religion is some kind of shamanic. There are shamans which know much about stars, herbs and illness. When children mature, ~ 12-14yrs, a Shaman leads them through a psychedelic ritual and they're very connected to some kind of metaworld.
At one day some hunters found a strange 'thing' in the woods (which is a rescue capsule from a spaceship).
Due the people live in peace, have a good connection to their "metaworld" and did not suffer from illness for hundreds of years, they have no fear.When they inspect the capsule, they notice 3 strange beings inside which seems to be dead or unconscious, the hunters bring them to their hunting-camp.
As the aliens receive the warmth of a campfire they begin to wake up.
The scenario from alien perspective:
The aliens are tourists which wanted to visit foreign galaxies. While watching this primitive culture of earthlings they got raided. The 3 aliens where part of a large group, but don't know what happened to the others. No communication possible.
For them this is a life threatening situation now. They will slowly notice that they have stranded on this planet (The capsule is not able to leave earths gravitation)
The aliens don't know each other, just got in the same capsule while evacuation. The capsule contains devices that can produce food out of any C O molecules, so they will not starve.
Assuming that the aliens have different characters, are not able to build a spaceship or interstellar communication device, they are forced to stay and die on earth.
Assuming this facts:
The aliens do not bring diseases and are very healthy
The people are very liberal. They accept 'things' which they don't know, as long as it doesn't harm them directly.
These days are glory days for the culture due they make (for their knowledge) giant steps in technologies.
Some of the elder are overwhelmed already, but they accept that. They know that they can't learn as fast as the younger ones, but don't try to slower the improvements.
The leadership of the culture are 3 people which are voted by the one person of every sub tribe. How the sub tribe chose this person is not declared and different from sub tribe to sub tribe.
The culture has no big enemies and life's very peaceful.
The aliens have different mindsets, their mind works in a very similar way as like the human mind. Let's say one is a ignorant and brutal guy who would sell his grandma for his advantage. The other ones are peaceful in general but would take every step to keep themselves alive.
The humans are curious and have no fear at all, maybe they should have a little due the fact that one alien is a ******.
The humans have merged but still don't think of themselves as a unit.
The aliens are not able to replicate or reproduce.
More specific question:
Are there examples in human history where a bunch of people from a (very)advanced civilization were stranded in a similar environment and how have they changed the less advanced culture?
If not, what do you think could happen after that event?