Humans did not have the technology or knowledge to build the pyramids
The pyramids at Giza were built 4,500 years ago before sophisticated tools were invented. The entire structure of the Great pyramid was made with great precision by unskilled labor. Even today the pyramids would be difficult to build. The granite blocks weighed on average 2.5 tons and the beams used in the King’s chamber way 60-tons. Many of the blocks were transported from hundreds of miles away. Without machinery or other advanced forms of technology moving these blocks would be impossible. Aliens could have used their super-advanced technology to either help humans move and cut the blocks or to move them themselves. Human technology was too primitive to build the pyramids. Aliens could have helped the Egyptians to build the pyramids at Giza.
There is a lot of evidence that humans built the pyramids, including the remains of the workers' houses, and Egyptian documents detailing some of the construction process.  The slow accumulation of human knowledge needed to build the pyramids can be seen in early attempts to build smaller versions using different techniques for block-cutting and transportation. Early Egyptian tombs were rectangular mastabas, these were improved upon by the Pharaoh Djoser (reigning from 2630 BC), who built early step pyramids. The Pharaoh Snefru (reigning from 2575 BC) attempted to create smooth-faced pyramids with varying success. The pyramids at Giza were a natural next step in the improvement of engineering techniques. Experimental archaeology has proven that granite can be cut with copper tools in combination with either wet sand or quartz chips, things Egypt has in abundance. Reliefs in Egypt show the Egyptians using primitive drills.  Following the principle of Occam's Razor, the simplest explanation is preferred when all other things are equal. The existence of aliens needs extensive proof before it can be given as a credible alternative to theories involving human tools.
[P1] Ancient humans could not have built the pyramids in ancient times without help [P2] Aliens could have helped them [C] Aliens helped humans to build the pyramids
Rejecting the premises