There are other works by Da Vinci in other museums too but again the Mona Lisa had become uniquely and superlatively special over his other works, and indeed, all other works of art.

This reminds me of Stanisław Lem's literature theory / theory of everything monograph The Philosophy of Chance [1]. One of the many claims defended in the book was that which works ultimately become famous art depends to a great degree on random chance.

The Mona Lisa is an unusually clear example. It doesn't even stand out among da Vinci's other paintings. Another example is music. Whether a piece becomes famous, isn't just influenced by whether it sound good. It also has to hit a specific nerve in the current zeitgeist. If the best House track of all time came out tomorrow, nobody would notice, because the genre isn't popular anymore. The artwork has to be at the right place at the right time, or it will be forgotten by history.

[1] https://en.wikipedia.org/wiki/The_Philosophy_of_Chance

Yes, I prefer "Woman with a ferret[1]" myself. A better work in almost every way.

[1] https://en.wikipedia.org/wiki/Lady_with_an_Ermine

Eh, I think it caught on because it's simple to describe. Da Vinci's other pieces in the Uffizi are a lot more elaborate and can't be summed up by "portrait with a smile". People like simple.