Violent, lively and brash, taverns were everywhere in early colonial America

I encourage you to make your argument with numbers. Even if I end up not agreeing, it will be a much better argument. I agree that there are downstream effects of violence, and it's a good point. It's still going to be dwarfed by all the boring stuff (e.g. diabetes). The fact that you think that the "dominant culture" (which one is that? "White" isn't a culture) has a "moral obligation" is, I think, just a result of how you've evolved to think about interpersonal violence through a moral lens and diabetes through a public health lens. If your goals have to do with "saving lives", or increasing the number of hours lived, or preventing unexpected deaths, even among specifically Black Americans, gun violence isn't the road to go down.

Painting the picture of violence as being visited upon e.g. Black communities by the world, or Whites, or the "dominant culture" is incorrect. The vast majority of murders in the Black population are committed by Black people. A black man is ~15x more likely to murder than an American who is not a black man. You can do some contortions to locate the causality elsewhere (like through a vague cultural legacy of slavery), but the evidence is overwhelming that violence is endemic to Black cultures in the U.S.

The sooner we all admit that to ourselves and start working on actual solutions that address the real problem, rather than pretending the problem is things like "they're poor and oppressed", the sooner we will all be able to help them build a better world for themselves. There are many poor, and possibly oppressed (if you are poor can you not be oppressed?) communities that do not have this problem of endemic violence, which is great evidence that the problem isn't one of mere poverty. And it's important to remember, too, that no U.S. populations are poor on a world scale. We're so rich our poor are too fat.