Ok, I'll play along.
"Why is there an unusually high number of black people being murdered in the US
relative to every other group???"
I think it has something to do with the jungle not being able to be removed or something. I forget how that saying goes.
Or, conversely,
"Why is there an unusually high number of black people being murdered in the US relative to every other group???"
Because they are disadvantaged and oppressed. The 25 y/o black male is trying to overcome 260 years of slavery that hasn't gone on for 150 years.

Because they are put down, turned away from jobs for lacking the ability to speak english, "forced" to live in low income areas, forced to go to schools that they themselves destroy and all around fucked in the ass by society, they are angry. They deserve to be angry. I would be.
So they do what any reasonable man would do when he is angry. They rob and kill their neighbors and destroy their neighborhoods.
In summation, it is a function of class struggle and the anger caused by the way society keeps the black man down and in slave chains.