The hashtag #BlackLivesMatter started with three black women, each of whom identifies as some form of LGBTQAP+. This is a good place to remind everybody that straight people are not allowed to use the q-word. It's not ours. Anyway, their names are Alicia Garza, Patrisse Cullors and Opal Tometi. You should read about their story and remember that we cishets are always ignoring the people who create the things we use, or just straight up stealing them, when they're not cishet.
But don't take it from me, because again it was a black non-straight person who said it.
A Herstory of the #BlackLivesMatter Movement
If you don't know where something originated from, it's probably because the creator was not very privileged at all.