How would you define black British culture and would you say it’s even a thing?

I had a heated debate with a friend of mine from Saint kitts and essentially what she said was that Black British Culture doesn't exist.

Her logic was that caribbean people don't share the same history or culture with Africans and aren't all black, and so shouldn't be put under the same bubble. Also, she said caribbean culture shouldn't be labelled as black culture because not all caribbean culture is African and again not all caribbean people are black. And then she explained that labelling it as black excludes non black Caribbeans from their own culture while simultaneously inviting people from foreign countries like Nigeria and Ghana. Then she gave me an example of how Africans feel entitled to Black British culture whether it be slang, sound system culture, nottinghill carnival etc, which causes them to gatekeep it from non black Caribbeans. Central Cee would be an example.

Also, she claimed that an overall black identity works better in America, because Black Americans share history and culture with one another, whereas "Black Brits" don't have a shared background.

Personally, I think she's chatting one bag of shit. We're all black at the end of the day and we're all a collective. But what's you guys thoughts? Would you agree with what my friend's saying or would you say otherwise?