Back then I would guess it was not called slavery. There were only two classes of citizens those born into royalty aka landowners and those born into servitude.
It was suppose to be an honor to be born into a class to serve the master(s).
Remember words meaning change over time. So do relationships. Only since the founding of America where a “middle-class” of free people were created did the term slavery take to a new meaning.
Land ownership was wide spread in ancient Egypt and not limited to royals. The priestly/royal cast were needed to settle boundary disputes, especially after the annual floods, but most of the land was privately owned. I don't think many land owning farmers worked on the pyramids, though I think their taxes paid for them. Slaves, by whatever name you want to call them, built the pyramids.
Going back further there'd been a hunter class, a gatherer class, a village class, a warrior class, ......
It is easy to imagine that Egypt had a "construction class" with it's own form of engineers, project managers, and acquisitions specialists.