The engineers were egyptians, the builders were egyptians, but at that time it was true that egyptians had slaves, but they were slaves, they did the physical work, i donno what kind fo work they ahd to do, it's so unclear how they managed to build such a thing...
But one thing I'm sure of, the engineers, the ones who knew how and why they did it, were egyptians, cause they were built on the basis of egyptian convictions, egyptians have always been constructing fancy tombs which contains their treasures and whatever that reserves their bodies to the glory of the next life...
The slaves according to my info, were israel's population and they didn't have the same convictions, they were different and they wouldn't even think of such a construction...
Plus the israeli led a simple life, like many other populations by the time, unlike ancient egyptians, who had expressed their greatness and knowledge in many things not just the pyramids...
And so the idea is purely egyptian, the engineers were egyptians and maybe maybe there were slaves doing the physical work..But since we donno how it was constructed from the 1st place we can't tell how it was built...
My historical info, says that Egyptians were secret keepers, they didn't spread their secrets to anyone, since all was written on papers of papyrus, and hieroglyph was hard to decode even for people who were livin by the time...
When the seleucid , pheniciens, roman, greek, jewish or isreali empires started to shine, egyptians were already loosing their former powers, and their alphabet their language were hard to decode still, and they lost their advantage when the byblos and what the greek improved to be the usable alphabet appeared...
It's known for a long time, that egyptians had their lead long before anyone, while others led a simple ignorant life, the egyptians were shining with power and knowledge, they had an amazing understanding for sciences...
Their secrets are burried with them, until now it's hard to figure out whatever thye did and how they did it...But if these techniques were common, why there was nothing as great anywhere else..(referring to the same time) and if it was known for other, I'm sure we would have tons of manuscripts that are telling us how these things were done...
But it was a secret..Yet unrevealed.