Like a Rollright Stone
was all there was to Rollright, then it wouldn't have been worth the trip. The inventions of tale-tellers can often give meaning to the meaningless, but in this case, they have missed the obvious.
The "King's" Stone is North-East of the "King's Men", aligned so as to mark that point on the horizon where the midsummer sun rises. The Earth has moved since then, but it's still near enough. Not many years ago, it would have been thought incredible that such primitive people could have managed any astronomical precision, but thinking has moved, too. Monuments from all over the world have been 'decoded', admittedly with variable credibility. (In all fairness, I must say that the case for an astronomical explanation for the Rollrights is extremely tenuous, but, work with me...)
At Rollright, the stones align to midsummer sunrise; no question. This elaborate sundial was built so that it only had any purpose for one short moment in the year. Beaker production would cease, and the populace would gather for a communal celebration of the longest day. The priests would probably point out, smugly, that they'd got it right again, what would you do without us. And everyone else would have a picnic.
There may have been the odd human sacrifice or so in the last four thousand years, but fashions come and go. More appealing was the practice of barren women to go to the King's Stone, and press their bare nipples against it, whether for a remedy, or for the sheer thrill of it, is not clear.
The male ritual was a bit more predictable. During the eighteenth and nineteenth centuries, it became the done thing to have a piece of the King's Stone, to take off to war as a lucky charm, and it was this chipping which created that cavity we see today. So it was sculpted, after all.