That is what propagandists count on. They pick a false "feeling" that people have, and they convince them that it is not only true, but worse than they ever imagined.
The statistics he posted are completely made up. The source (crime statistics bureau San Francisco) is completely fake. They are just pulled out of thin air.
Here are the fake statistics next to the real statistics from the FBI:
So everything was blown way out of proportion to make black people seem like they were killing everybody, and white people were not killing anybody. The idea of the meme is to push the false narrative that white people are just victims of black people, and black people are out killing everybody. Of course, the reality (which to your credit, you correctly predicted) is that the vast majority of white homicide victims are actually killed by other white people.
But whoever created that meme knew that a lot of people are ignorant to the facts, and that their prejudice would make them believe anything that confirms their prejudice. That's how effective propaganda works.