You're skipping a lot of context here. Ancient Babylonian scribal schools were for a small elite—hardly universal childhood education. Medieval Europe's "regression" had a bit to do with the collapse of the Roman state, plagues, and centuries of instability, not just a lack of ambition. Comparing literacy rates across millennia without mentioning population size, language complexity, or what “schoolchildren” even means is a stretch.

History isn't exponential—it's bumpy.