I've encountered this sort of point before, you'll likely find many examples right on Lemmy. Does the US "not have culture"? Does it have lots of different cultures? Has it just been so good at spreading culture that everything feels American?
https://www.youtube.com/watch?v=Rr8ljRgcJNM
Post picture is something that feels uniquely US, for better or worse
Definitely not a monoculture, but there's a few things that sharply contrast when compared to other countries. The biggest one I've noticed is strong individualism that sometimes manifests as rights and sometimes manifests as bootstraps. Another is using courts instead of regulating corporations (which they then avoid by binding arbitration etc) as well as a general litigiousness. Colonialism in definitely not unique to the US.
Some things that I think are unique to Usonions but not universal among them: mormons and evangelicals (though they're spreading), football, car culture (to the extent that it shapes laws, city planning, social life, employment, etc.).
I'm sure there's more but that's what's off the top of my head.