I`m quite happy to agree to disagree over this :-)
I don`t include the neolithic / bronze age people under the title `ignorant and superstitious people` simply because I presume that they were not ignorant about why they built there own structures.
It seems highly unlikely, to me, that any knowledge of prehistory is retained in folklore. We have very little knowledge of many times and events that occurred way after the eras that we are interested in. The Druids and whether there really was a King Arthur are a couple of examples that immediately spring to mind.
Although I think that the folklore about these sites does more to muddy the waters about them than to make things clearer, I do agree that the tales have, in the more recent past, served a useful purpose in helping to preserve them.
Most of the tales seem to follow certain patterns, e.g.
The devil / a giant / etc threw it at a church / his dog / etc and missed.
Dancers turned to stone.
At midnight, they all go down to the stream for a drink.
Someone took ten horses to drag a stone down a hill, he was plagued with misfortune until he used one horse to drag it back up again.
I just can`t see how such tales can add to our knowledge.
baz