If we HAD to build a pyramid, we could. It is that simple. If we needed a bigger crane, we could build it. It is that simple. We don’t have any stinking leaders who insist on that sort of rubbish these days, so we haven’t tooled up for it.
That goes without saying, but that's not the point of the conversation, which is -- how did the ancients build something that we don't have the tools to build in the 21st century?
To make my point even clearer, let's roll the clock back a mere two centuries and ask the question again. Could the people of 1819 have duplicated the Great Pyramid? How about the people of the 1600s? We're only talking the blink of an eye in time, compared to 2550 BC, which is 4,570 years ago.
Surely, the Pilgrims and their contemporaries possessed greater knowledge of the material and building sciences than the people of pharaonic times. So what do you think? Could the people of that era have built an exact replica of the Great Pyramid if they'd had a mind to? I highly doubt it.
Ultimately, it beggars belief that the ancients possessed anywhere near the technological prowess required to construct that monument. Going by the evidence alone, it's not possible to prove that they did. To this day, it has only been surmised that they could, and unfortunately, is now taken as an article of faith amongst egyptologists and the world at large that they did.