I feel that although I cannot relate to being a black person who has white people telling them how they should feel (which is the topic in this thread), although it's not completely the same I am a woman who has had men tell me how I should think/feel/behave about things that only impact women. I know how angry it makes me feel with someone who has no lived experience of what I've lived through thinks they can tell me how I should feel about something from a position where they feel they know more about the subject than I do - is that what they call "mansplaining?"
Anyhoo, I'm off topic, but because I can relate to the horrible feeling of "how can you speak on my behalf about things that don't impact or concern you", I can apply that to this topic so when I hear black people say "white people can't speak for me", I understand. I get it. I'm not angered by it, or feel like it's dividing us, they're correct! White people cannot comment on or input to the discussions regarding how black people feel and their lived experiences - I have not lived life as a black person in England so I cannot offer anything useful or constructive. All I can do is listen and learn.
If what I feel as a woman being "mansplained" to about things which only impact women is just a fraction of what people from other races feel when white people explain racism to them and what should/shouldn't be offensive, I can completely sympathise and understand why it's inappropriate. I also understand the anger when they're told that white people should get a say on how they're feeling - one writer of an article I was reading today (I apologise - I've read so many of these articles today I can't remember which one it was in or who the author of this article was so will try to find it) said that being told how to feel by white people about racism brings her back to her ancestor's experiences with white people telling them, forcing them, to live a certain way, only use certain schools, certain amenities, excluding them from things, it reminds her that the battle isn't over. She still can't live her own experience without white people telling her how it actually is when she, as the one who is experiencing it, feels differently.
We are all part of one human race, but we all have different lived experiences with other people and the world depending on our age, sex, race, religion, so many different factors. We can work together, come together, progress together and solve these problems together but we cannot override each other, dismiss each other, ignore the lived experiences over the textbook idea of what something should be.