You didn't know that the Egyptians and other ancient people knew astronomy, and believed that the stars were very important? The night sky is very bright without electric lights interfering. Stonehenge, the Pyramids, Mayan structures, many others were aligned with movements of the moon, sun and stars. These people were not ignorant, they were intelligent, and very interested in the natural world around them and studied it. Without technology, they were very creative at solving problems. For example: moving large blocks of stone:
Solved! How Ancient Egyptians Moved Massive Pyramid Stones
It may be more exciting to think aliens gave them help, but making facts fit a theory instead of the other way around is not good science. My mind can comprehend that.