I think that those who have mentioned writing have hit at the crux of the issue. I don’t think we can really know who built things when there is no written record, because we can’t know what they called themselves. We can know that they existed and slowly build up a picture of their world from the archaeological record and using what we know of similar cultures which have been documented.
I am a researcher (LaTrobe University, Melbourne) specialising in the way indigenous cultures store masses of practical information when they are totally dependent on memory. I then apply that understanding to the archaeological record. I have written about Stonehenge, Chaco Canyon (Ancestral Puebloan like Mesa Verde mentioned above) and the hunter-gatherer-fisher mound building site of Poverty Point in Louisiana. I’m now working on nearly all the sites mentioned above.
I have even dug on the Ness of Brodgar! I was a guest there talking about my ideas on the purpose of these monuments the world over so they trained me and I pretended I was a real archaeologist. It is simply amazing!
My book has only just gone out to journals for academic review, so I am waiting nervously for the response. But the theory has passed every review so far.
Basically (to reduce a PhD thesis and academic book to a few paragraphs!) mobile tribes, like our Australian Aboriginal cultures, use the landscape to act as a memory aid to the vast store of practical information, like animal behaviour, plant properties, navigation, genealogies, laws, intertribal agreements … the list goes on and on. Settled pre-literate cultures like the ancient Greeks, used street-scapes and buildings. It’s called the method of loci and the most powerful memory system ever developed, so it is still used by all memory champions today.
My research shows that all non-literate cultures use a form of this memory method as well, and this can explain the structures of the enigmatic monuments they build in the transition from a mobile lifestyle when they used the broad landscape, to a settled farming culture when they used the built environment.
Many of the monuments we see, such as Stonehenge, the Ness of Brodgar complex, stone and timber circles all over the world, such as at Gobekli Tepe mentioned above, demonstrate exactly what the elders would have needed to localise a memory system based on the broader landscape when they settled.
Who built Stonehenge? The Neolithic Britons did. But I don’t think we can be any more specific than that. The Ancestral Puebloans built Mesa Verde and the Ancestral Zimbabweans built Great Zimbabwe. Great Zimbabwe doesn’t match my pattern, though. I use that as a counter example, because it is a much larger community and has a hierarchy with leaders with individual wealth at the helm. The others we’ve mentioned aren’t like that - they are materially egalitarian. That makes a massive difference as well as to what is left - but too much to write here - I have already waffled on too long.