there are legends about merlin probably written in the ~800-1200 CE zone that identify Merlin as one of the people who participated in the building of stonehenge. which would have probably made sense if you were a peasant in like the year 1000 living on a farm in britain who saw those rocks and thought "damn those rocks look old as fuck. i bet they're like four hundred years old" and that would have been, probably, a pretty decent guess because everyone and everything you know basically began a couple hundred years ago and those rocks have been there the whole time. so you think "yeah a wizard probably put those rocks there like five hundred years ago" and how would you, peasant, know that in fact those rocks were (likely) there not a few hundred years ago but in fact a few thousand years ago (current estimates put them constructed about 3000 BCE).
and to the medieval peasant it's all ancient and unknowable because all they know is that many years ago there were people called "Romans" who built grand monuments and they were destroyed by the heathens before God came to Britain again, and God came with different Romans this time around. And these days no one builds great stone circles anymore!
And in our time now some 1000 or so years later we can identify that some five thousand years ago a group of people huddled together around this strange circle and did [actions] involving [bones] and chiseled to create trilithons and standing-stones that would last longer than anyone had memory for, longer than humans can even conceptualize, longer than the cultures that built them and the cultures that usurped those cultures and on and on until at one point the Romans saw the stones and possibly guessed that at one point there were architects here too, and the peasants of the year 1000 saw it and assumed a wizard did it, and the scientists of the year 2000 saw it and dated it earlier than either the peasants or the Romans.
and because we lack some sort of magic we can't peer into the eyes of the people who built it so we can only assume that it was for the movements of the stars or the way that torch-light cut through the stones at the right time, or perhaps the way that people were meant to stand amongst the stones (or in front of the stones?) and pile (or place?) the animal carcasses (or just the bones?) or the human carcasses (or just the teeth?) into the stones (or into the ditches?) and maybe the way that the people stood as they performed the Actions was all it was about. And we'll probably never know, but we know they were people who did it. and that it was important to them
