Yeah, this shared artifact - aka "social object" - is the key. It's why the Internet culture is defined by things that "went viral" - because those are the ones everyone saw, and everyone can expect everyone else saw them too.

As for the sculptures and paintings of Mary, etc., I'd say they are all boring and entirely interchangeable, but that's because I have no connection to any of them. Each such work is meaningful to the community that had a personal connection. But I'd say none of them are culturally important, except those individual ones that for some reason (like being very old) become widely known among people outside artifact-adjacent community.

Side point: culture always has a scope. Something may be important cultural object for the city I live in, unremarkable for anyone else in my country, and entirely unknown the rest of the world. With the Internet enabling arts and entertainment on demand, there is little overlap between communities we live in and the entertainment choices of individual community members. We end up having communities with no culture.