So, in the least-racist way you can, please imagine black people are hideous violent monsters who are physically stronger than humans and have large protruding fangs. Then understand in your kind human heart that we should accept these hideous monsters as equal to us normal, beautiful humans. And to demonstrate that, here is a heartwarming tale of an orc who proves himself to be One Of The Good Ones -- he even voluntarily cuts off his fangs! Let's pause for a moment and process that little bit of symbolism: To become good, he simply has to suppress the naturally dangerous element of his biology. That's all.
Yet it's the kind of parable that turns up over and over again in science fiction and fantasy stories that are reportedly trying to convey a message of tolerance. "Look, we get that you're having trouble seeing minorities as humans, so perhaps it would help if you imagined them as something that is A) objectively not human and B) inherently dangerous."
Doctor Who wanted to do a story about accepting Muslim refugees. Neat! So they recast Muslims as Zygons, space refugees who come to Earth after their planet is destroyed. They can "convert" others into Zygons, and they're shapeshifters, so they can secretly be anyone. Their true form is what I'll call a devil's octopus, a hideous red monster with suckers all over their bodies. Also, they can shoot lasers from their hands that reduce normal humans to a pile of electrified skin and hair.