The problem is, we're meant to assume (via the EU chronology), that the Republic is over 25,000 years old. Even with retcons in place, some kind of GALACTIC Republic has existed all this time. That means at the bare minimum they had to have FTL technology. Otherwise you can't colonize, much less keep any semblance of order or government in a galactic society. A galaxy is a big place after all! So their tech level has to be at least a certain height all this time. Arguably they need other dependant technologies in order to make the FTL stuff work (assuming it's Hyperspace and not some other form long since abandoned), like hypermatter and all that stuff. Likewise the Order of Jedi Knights is supposedly 25,000+ years old. However in the ROTS novel it's made clear that the Jedi Order existed BEFORE the Republic was created (unless that has been retconned to mean just the Republic of the last 1,000 years). Of course that doesnt mean necessarily that they had lightsabers back then, but still.
Oh, and we have a fairly good idea how the pyramids were built. We could actually make much better pyramids today. The only thing stopping it from happening is that we have far superier building methods today (the Egyptians could not have hoped to build a skyscraper, since they didn't know how to build with steel and also lacked elevator technology). Sure, stone lasts, but let's face it, we could build one in a shorter time and with more "perfect" stones, the thing is, it would cost so much. Who would want to live in a big pile of rock in the desert that isn't very comfortable (these were tombs after all, not luxury homes), when you could build tons of apartments or houses for the same price?
It's actually a common sci fi cliche that all old technology is "built to last." In Star Trek (and Star Wars EU) they are constantly digging up some piece of tech from a bygone era that still runs or suddenly springs to life and threatens everyone. Stuff that looks super primitive in reality is super advanced. Like Flintstones era computers made of rock or something.