Black people save white people all the time in movies, just ask Will Smith. He's saved a bunch of white people in Men In Black I and 2, saved a bunch of them in Independence day, saved white people back in the day in Wild Wild West, saved a bunch of white people in I, Robot, saved a hopeless white dude in Hitch, saved white people in Hancock, saved a white kid and latino chick in I Am Legend, and saved some white people in Seven Pounds. So dont say white people are saving black people all the time because will smith, the highest earning actor on the planet, has done it for the majority of his career.
PS I personally dont think this movie is really all that much about race just a down guy helping an even more down guy.
PPS If anyone needs more examples of black people saving whites i got plenty more, so just ask