Structures like Stonehenge and the pyramids are structures that have baffled scientist and archaeologist for generations. Figuring out how primitive cultures moved such large structures without modern technology enabled casual thinkers to accept supernatural explanations like aliens since a proper, grounded explanation did not exist. The first person to explain how the ancients may have moved such large stones was not an archaeologist, physicist, or a scientist, but a retired construction worker from Michigan named Wally Wallington.
To be clear, a number of viable theories existed before Wally’s efforts, but a lot of them were impractical, like using oxen and stone ball bearings to drag the stones across England or unsuccessful like an attempt to transport the stones via boat.
More recently, a professor at the University of London and his students developed their own method to move stones and also constructed their own Stonehenge, but it required more people.
Although Wally is not a scientist, he still developed a theory and tested it, and it holds up under the scrutiny of professionals. It still may not be the exact method used to create Stonehenge, but it proves ancient civilisations definitely had the capability to create great things without the help of aliens.