Honestly the best thing for people to keep in mind is that humans were really good at moving giant stones long distances at that point in time so they could come from pretty much anywhere. There is a video on Easter Island statues where they figured out a way to walk the statues down to the water's edge matching oral tradition descriptions and there is a guy who moves huge blocks multi ton around with a similar technique.
When people did it full time for generations I bet they had even better techniques!
Another great example is probably starting a fire only using materials from the environment. Anyone can learn how to do so, but most people never have it come up during their lifetimes!
Someone who knows knapping and how to start a fire is 90% of the way to surviving long term in temperate wilderness. Yeah, building shelter and knowing what to eat are important too, but making sharp things and creating heat are the two things that are make or break in a survival situation.
Speaking of not leaving written records, a large number of cultures had strong oral traditions that passed information down for thousands of years. Oral traditions have the additional benefit of being taught personally, allowing for time to ensure it is actually understood! It does have the danger of being lost when the culture changes significantly.