Did the Egyptians really build the pyramids alone or is there something we're not being told?

Been down this rabbit hole for years and I still don't have a satisfying answer. The precision on those blocks is what gets me every time. We're talking tolerances tighter than a sheet of paper on some of those limestone joints, and supposedly done with copper tools and wooden sledges. I'm not saying aliens, before anyone jumps on that, but there's clearly knowledge involved that we either haven't accounted for yet or has been deliberately kept out of the mainstream conversation.

The lost civilisation angle makes more sense to me personally. Graham Hancock gets a lot of grief from academics but some of his arguments about a pre-flood advanced culture are hard to just dismiss outright.

What does everyone else think? Any of you looked into the acoustic resonance theories around the King's Chamber? That one's always struck me as particularly worth exploring. Would love to hear from people who've actually visited Giza and got that up-close look at the stonework.

Not really my usual territory but the engineering angle genuinely bugs me too. What I keep coming back to is this - why is there such a massive gap between the complexity of the pyramids and literally everything else Egypt was producing at the same time? You don't just suddenly build the most precise stone structures in human history and then kind of... plateau. That trajectory makes no sense to me. @JamesWilliams have you looked into the acoustic resonance stuff at all? Some researchers reckon the internal chambers were designed to produce specific frequencies. Could be nothing but it doesn't fit the "ramps and sleds" explanation either.