This is true, but it's a tad misleading. A very large chunk of the murders in US cities are black-on-black. I read a study somewhere a few years ago, maybe a decade ago... and I won't be bothered to find it now... so take this with a grain of salt... But when controlled for inner city black neighborhoods, the US would fall somewhere in the middle of the EU as far as homicide rates are concerned. I'm not trying to go for a full 1488 race-realist tism fit here... but the numbers are what they are. The homicide rate is insanely inflated by a very small slice of the general population, namely younger black males, which might account for 5% or less of the total population living in an even tinier sliver of overall land.
As far as the whole thing with BLM talking points in general, just stop the pointless "war on drugs". That alone would save more black lives than a limitless number of "racial sensitivity" powerpoint slide shows for cop training. If you want to pick an arbitrary date and consider the start of that particular brand of prohibition to be the founding of the federal Drug Enforcement Agency... Then you've got a roughly 50 year track record of bottomless government boondoggle that hasn't stopped a single junkie from getting their fix for very long... Granted, widespread legalization brings it's own set of issues... but in the grand scheme of things, the genie is out of the bottle and historically, government prohibition has only proved itself capable of creating black markets / organized crime.