It's not really a commercial trope so much as a TV sitcom trope, going back at least as far as the Honeymooners.
It's also not as common as it used to be, as far as I can tell.
Edit: I've been thinking about it, and I don't think I can recall ever actually seeing "black male rescuing a white woman from a white male" being used in an advertisement, anywhere. Typically such a motif is used to present the black male as a threat, not as somehow heroically superior to his white counterpart.
Even then I can only recall its use in political advertisements (such as the infamous "Willie Horton" ad) and maybe very old movies.
It's also not as common as it used to be, as far as I can tell.
Edit: I've been thinking about it, and I don't think I can recall ever actually seeing "black male rescuing a white woman from a white male" being used in an advertisement, anywhere. Typically such a motif is used to present the black male as a threat, not as somehow heroically superior to his white counterpart.
Even then I can only recall its use in political advertisements (such as the infamous "Willie Horton" ad) and maybe very old movies.