Many people that are great at painting now probably never "studied" painters before them. They just, experimented and practiced for years. All you need is the real world and practice.
Besides the general absurdity of your claim, how are you surprised that an artist can become great solely by drawing from the world around them? That’s how almost every single artist becomes great. It’s literally one of the most basic forms of practice.
The Romans had industrial scale milling in modern-day France, enough to feed 10-40k people. https://en.wikipedia.org/wiki/Barbegal_aqueduct_and_mills
Antikythera mechanism predates that by 500 years.
I'm curious what technologies were lost for thousands of years. Roman concrete is essentially lost, Silphium is extinct, flexible glass, and Greek fire.
Modern technology is lost in bits and pieces: Starlite is one example. Unknown unknowns are the most elusive.