The working class vote is not exclusively white, of course, but it is predominately white because we live in a predominately white country. This isn’t a race issue though, and I don’t think it’s helpful to get preoccupied with that.
The only way that Labour is going to be a realistic choice for many voters at the ballot box in future General Elections is to regain the center-left ground. I know that’s anathema to many people on here, but the reality is that for many of Labour’s traditional working class voters the party has gone too far left of center, allowing the Conservatives to occupy the center ground.
Because of Momentum’s influence, however, I’m not sure if their members would want to even contemplate that. Unfortunately, until this existential issue is confronted Labour will not win another General Election for the foreseeable future.