My 17th Century Dutch isn’t so good but I can still look at the illustrations in Johan Picardt’s 1660 book “Korte beschyvinge van eenige vergetene en verborgene Antiquiteten” eg here, here and here. Mr Picardt is considered the founding father of the study of archaeology in the Netherlands. The drawings seem to show the hunebedden being built by giants and dwarfs. But the dwarfs seem to get the raw end of the deal as the giants end up eating them. That’s certainly what it looks like at any rate.
Great set of images Rhiannon.