The ancient Egyptians utilized neither wheels nor work animals for the majority of the pyramid-building era, so the giant blocks, weighing 2.5 tons on average, had to be moved through human muscle power alone. But until recently, nobody really knew how. The answer, it seems, is simply water. Evidence suggests that the blocks were first levered onto wooden sleds and then hauled up ramps made of sand. However, dry sand piles up in front of a moving sled, increasing friction until the sled is nearly impossible to pull. Wet sand reduces friction dramatically beneath the sled runners, eliminating the sand piles and making it possible for a team of people to move massive objects.

https://daily.jstor.org/scientists-have-an-answer-to-how-the-egyptian-pyramids-were-built/