Chauvet Cave and Lascaux are similar (lots of overlapping paintings of large animals), but some 16,000 years separate them. Is that individual self-expression? It looks to me like entrenched tradition.
Stencil paintings of hands are a common theme, but bizarrely are found all over the world: Argentina, France, North Africa, Australia. This too can only be a meme, I think. Possibly the method, spitting out paint, was the meme, and the idea of making stencils of hands arose naturally by accident in all these places, but even then there is no sign of real individual self-expression going on. It's also intriguing to me that three of the places I mentioned (on three different continents!) include stencils of animal hands (large birds or lizards).
There are too many things that are grouped under the same word: 'art'. Objects which serve different functions should not share the same name.
Name one.
Perhaps one can mention artists like Caravagio and El Greco. But all such artists addressed themes that were common: the bible and the clasiics. The unique thing about the romantic movement was that they placed immediate human experience above god and godliness.
Honestly, check out Goya's black paintings and you will see what I am talking about. I challenge you to find an equivalent precedent.