The best description I have ever heard to explain BLM was a dessert scenario.
There is enough pie for everybody to have some, but somebody starts cutting and I wind up with none. So I try to get your attention, "I don't have any pie. My pie matters!" then everybody shouts "All pie matters!" and everybody but me continues eating, because I still have no pie. So I say it again, "My pie matters!" and everybody repeats that "All Pie Matters!" and continue eating their pie....
Frustrating as it is, clearly they believe that all pie matters, but since they have theirs they do not seem to care about mine... everybody understands fairness, but one of the statements works towards fairness, the other simply recognizes it but does nothing to fix the problem.
I believe that every life matters, therefore "Black lives matter".