Even marxists don’t simplify the classes as much as that diagram suggests. It’s missing peasants, artisans and the petty bourgeois. It’s also never been as simple as capitalist vs working class. Capitalists regularly fight amongst themselves as do the working class. This whole idea of class struggle being the only struggle is so oversimplified it’s kinda silly.
I don’t think it’s honest to frame it in generational language either btw. Though that is a component of it.