There are about 118 known pyramids in Egypt, and from the oldest to newer ones they show distinct evolution. And there are at least a few “failed” pyramids, that partially collapsed due to poor planning.
The very earliest (not part of the 118), are naturally occurring, because of wind erosion, so it’s easy to see where they got the idea.
A couple of decades ago, The Smithsonian proposed a simple method to get the stones from the river to the pyramid site and then up on the pyramid itself.
You get two sets of four reusable wooden rockers, held together with wooden pins. This turns a rectangle into a cylinder, which just takes a fraction of the time and effort to move.
Then you use the existing technology of dirt ramps to get them up to the pyramid you desire. The Egyptians were experts at building dirt ramps, and even the Romans learned from them.
As long as you plan ahead, any tunnels and chambers in the pyramid are just integrated into the construction as you build.
Then, after you have emplaced the capstone, you just sweep all the dirt away and there is your pyramid.
It all uses just a fraction of the time and the manpower compared to other methods.
It was a break room for the engineers....................