When the Black Lives Matter people say "Black Lives Matter", they don't mean it. They just want to use it as a cudgel. They want to use it to berate those who say "All Lives Matter". "Black Lives Matter" to them just means "Only Black Lives Matter" and as I said, it doesn't really mean even that.
How can we be sure? Because the Black Lives Matter people don't want black policemen to be included among those whose murder would be a hate crime under a proposed federal law.
To be fair, the Black Lives Matter people don't want the murder of any policeman to be considered a hate crime. And they are fairly up-front about their bigotry, saying "it’s not the color of their skin, but the color of their uniform". Clearly, only some black lives matter to Black Lives Matter.
Or, as I previously noted, Black Lives Matter, But To Whom?