As an intellectual challenge, I've never doubted the plausibility of the pyramids being assembled from man power. I'm completely in agreement that a work force could be assembled to move stones, assemble them to a high degree of accuracy, and a system could be conceived as to how to move them into place at all heights of the construction of the pyramids.
But I'm seemingly far more distracted by some of the presumptions of how the stones were carved. This is where I part ways on that school of thought. The sarcophagi at the Serapeum, most of Christopher Dunn's observations in this regard, etc etc, all become an impasse for me when considering a lower level of technology could have been used.
The beautiful carvings of Greek and Roman culture show an amazing ability using hand tools. Consider David. But there is a chasm of difference between subjective work of asymmetrical sculpture based on impression and precision work for seemingly no reason at all. This is where I lose faith in a seeming myopia of Egytology. This is the subtle instinct I'm referring to, and its clear absence in those who over look it.
So accepting the presumption that Egyptian culture could have assembled all these sites, but they couldn't have fabricated many of the carvings, it points me in one of two directions. Alien assisted Egyptians or artifacts from a far older culture that were inherited by the Egyptians. And I far prefer the latter.
But if we are limited to the only kind of proof being circumstantial evidence of the context of findings around the site, you can see how a culture that takes over a previous more advanced culture's left overs can be a huge source of misdirection. I think we are underestimating the degree of damage done by that layer of black micro crystals and carbon. I suspect comet damage could fairly easily melt our pop cans and Styrofoam plastics in a flash. Its really no wonder the only things left were huge stone construction. Anything else must have succumbed to the scorch power of a comet or the aggressive oxidization of flooding. The only stuff left would be burrowed deep in the earth and we won't find that stuff until we have huge advancements in technology, or power ball odds of luck. And considering the devastating implications on all religion around the world, if anything is found, there's a fairly good reason to keep it under wraps so as not to inspire terrifying reactions.
With respect to the pyramids, I'm getting the impression there are some that are old, and there may be some that are copy cat constructions, so there would be many pit falls to evaluate them all together with the same assumptions.