Take a look at this:

Image

This is in the Museum of the Palazzo Massimo alle Terme in Rome, and it comes from an ancient Roman Villa in Rome. Probably painted in the first or second century CE. There’s walls of this stuff in the museum.

It’s not realism, but minimalistic sketches that, in many ways, outdo realism in artistic quality. To me, this looks more like something that you might find in Leonardo’s sketchbook than on the wall of on ancient Roman Villa from 1200 years earlier.