Let’s talk about the obvious things first.
The first obvious thing is that Mona Lisa was astonishingly beautiful back in the day.
She might not have Angelina Jolie’s cheekbones or Emma Watson’s eyes, but that’s not how people saw her 600 years ago.
The Ancient Greeks glorified women with bigger noses and round cheeks. In the Middle Ages, round figures were seen as a symbol of health and status. Women plucked their hair just to make their foreheads look taller.
Yes, Mona Lisa was a babe.

Beauty standards going way back. Left to right: 1. Leonardo da Vinci (Wikimedia Commons) 2. Sandro Botticelli (Wikimedia Commons) 3. Random Greek statue (Wikimedia Commons). Edited by me.
The second obvious thing is that Mona Lisa was insanely photorealistic for the time. In 1500s people had a very primitive understanding of how physics work. I mean, it was 200 years before we discovered gravity.
Most artists were having trouble painting shadows correctly…