None of which, regardless, leads me to a conclusion that supports cycles upon cycles of advanced civilization stretching back tens of thousands if not millions of years let alone any capable of building the megalithic monuments of Egypt.
Incapable or didn't have a reason?
It's a chicken or egge argument, I know, but what if the devastation cause by the Younger Dryas Event impacted our collective psyche so badly, this entire thing we call 'civilization' sprang from it?
Meaning the ancients did have civilization, even highly advanced civilization, we just don't recognize it as such because it's different in nature.
Agriculture is often named as a prerequisite for civilization. Even though humans for tens of thousands of years were perfectly capable of civilization, it didn't happen because they didn't have agriculture.
Let's take the highly conservative wikipedia, and what it says about the "History of agriculture"
Agriculture involves the domestication of plants. Data from molecular and archaeological research generated over the past 15 years now makes it clear that agriculture began independently over a much larger area of the globe than was once thought, and included a diverse range of taxa. At least 11 regions of the Old and New World were involved as independent centers of origin, encompassing geographically isolated regions on most continents, but several more have been suggested.
It developed independently in at least 11 regions.
Doesn't this strike you as very strange?
For 50,000 years humans didn't engage in agriculture, then, after several thousand years of global devastation and upheaval, it develops independently all over the globe.
Either an ancient advanced civilization didn't engage in agriculture like post-glacial humans did, or all traces got erased. But the knowledge was clearly there. At least I can't think of another way to have have it spring up independently like this.
So perhaps we don't recognize the traces they left because they did things differently.