Let me guess, black people dug them. (I didn't read the article 😁)
Stonehenge isn't old. We have footage of them building it with steam powered equipment in 1903. They dug everything back up in 1956 and used modern equipment to line everything up then they used Readymix cement to fix everything in p;lace. A whole bunch of people were there and there are pictures and footage. Also, the Romans had that Island for near 400 years. They made a bunch of detailed maps that show meadows, rivers, mountains and even notable rock outcropings. All were used for travel. Something like Stonhenge would absolutely be on those maps as a marking point. None of the Roman maps have it because it wasn't there.