Police have been killing Americans since at least the 1900s
Much longer ago than that.
What's new is that we have the deeds captured under multiple angles in full HD, and still around 30% of the country believes the victims were actually the aggressors and deserved to die. They're so indoctrinated that they're able to rationalize away their own eyes' evidence. And they feel comfortable enough in the current environment to try and gaslight you about it.
Not on high res, widely distributed video. Not, immediately after that video, telling us we didn’t see what we saw.
The game has changed.