The point of Heller was saying that guns in common use couldn’t be banned (and was affirmed to apply to states as well as D.C. in McDonald v. Chicago); many of the gun control laws that prevented ownership of firearms were racist in origin, and so saying that the gov’t can’t do that thing has the effect of invalidating laws rooted in racism.
One of the people that was originally part of the Heller case was a black community activist, and the reason she was removed from the case was lack of standing. She had not actually applied for a permit to own a firearm in the city–because she knew it was illegal–so she got kicked from the case. Heller was the only one of the original plaintiffs that tried to apply for a permit, hence the reason he’s the face. (Heller–the person–was/is a douchebag.)
The fact that cops murder black people is a problem, sure. Do you think that they’re going to stop if black people aren’t armed? The NRA is a rotten organization; I’d recommend the Firearms Policy Coalition as being one that’s more representative of the interests of gun owners, rather than christian nationalists.