I was taught in school that Perspective was invented in the Renaissance, and before that all art was flat. This is obviously not true to anyone who's studied greecian art beyond a pop-culture level, but that's the level most people have.

It does seem to have waxed and waned; going in and out of popularity to the point of being a lost art multiple times. Wikipedia doesn't go so far as to divide it into eras, but given the time gaps, it's possible that there were multiple "inventions" of perspective in the sense of formalized techniques and pedagogy. https://en.m.wikipedia.org/wiki/Perspective_(graphical)