1. There is an enormous period of time in deep history that lead up to the Dynastic period where these people developed their abilities to produce all that work, but all evidence of that period of necessary 'stages of developement' has been wiped from the record somehow from some other unknown cataclysm.
I have no reason to dispute number 1; in fact, it seems there is some evidence and growing mainstream academic support for the Younger Dryas impact cataclysm.
However, with respect to scenario number 3 where you hypothesise:
3. Egyptians just woke up one day totally imbued with advanced abilities to fabricate megalithic work and someone made a lucky guess about precession.
I must disagree. There is clear evidence of evolution in dynastic tomb building.
There are in the First Dynasty some tombs at Saqqara with a small hill or pyramid shaped structure over the burial chambers. These hill shaped structures are built in all cases inside a mastaba.
The mastaba evolves into the step pyramid, such as Djoser's. The third dynasty step pyramids are of kings whose reigns are deemed to have been very short and is perhaps why none was completed.
There are 'dummy' pyramids such as the pyramid of Ombos which contain no burial chamber; their purpose remains unknown dated to the end of the third or beginning of the fourth dynasty.
These step pyramids evolve into true pyramids, such as Snefru's at Meidum which I understand to have been first built as a step pyramid and then re-designed and extended, which is perhaps a reason for its collapse - though there are others here at the forum, like Thanos, Martin, Warwick and Avry, who are far more knowledgeable on the subject than me and can better explain this to you.
The Nabta Playa calendar circle suggests a pre-dynastic civilisation with an astronomical knowledge and interest, stretching back to at least the fifth millennium BCE though the region had been populated for millennia by then, so no, the dynastic Egyptians didn't suddenly develop an interest in precession out of nowhere but perhaps inherited a body of knowledge that arguably stretched back millennia by then.
Edited to add: Astrophysicist Thomas G. Brophy suggests the hypothesis that the southerly line of three stones inside the Calendar Circle represented the three stars of Orion’s Belt and the other three stones inside the calendar circle represented the shoulders and head stars of Orion as they appeared in the sky. These correspondences were for two dates – circa 4800 BCE and at precessional opposition – representing how the sky "moves" long term. Brophy proposes that the circle was constructed and used circa the later date, and the dual date representation was a conceptual representation of the motion of the sky over a precession cycle.
Edited to correct typos. It's late and I should be in bed!
Edited 4 time(s). Last edit at 06-Apr-19 22:31 by eyeofhorus33.