It is probably a combination of many things.

It is made by one of the famous and influential person in history. It is aesthetically pleasing, a bit mysterious yet accessible. The technique is interesting. And with the 1911 theft, it comes with an exciting story.

Taken individually, none of these qualities are that remarkable, but it is the combination, and a bit of chance.

It probably got picked up and used as an example of ‘famous stolen art’ in a movie too, which skyrocketed it.

It wouldn’t be as famous as it is if it didn’t have something remarkable about it. Art is about creating emotion in people and whether you think it has good “aesthetics” or not, the Mona Lisa captures people’s imaginations almost more than any other painting in the world.

For me there is a mystery and secret in the Mona Lisa which doesn’t exist in other paintings that might show great “skill” and in the end, art is about emotional impact, not what some critic thinks is “skillful”

Sometimes “remarkable” means a meme randomly caught on, or a good marketing team. There are plenty of famous things that are poor imitations of relative unknowns.

There is something uncanny in this painting, my take is that it’s not a woman that was painted.

Have you seen what other people were painting in the early 1500s? Leonardo's work is extraordinary for his time. Comparing the Mona Lisa with later art is a bit like measuring somebody while you're standing on their shoulders.