Uh, no. There are fifty five formally recognized by the PRC including ones they're actively trying to exterminate (e.g. Uyghur). Within the Han community there is still a significant amount of diversity including countless dialects of the Mandarin and Cantonese languages. Your comment is a bit like claiming that with all the white people in Europe, it's not a very diverse place.
In contrast the Japanese government recognizes about four indigenous races.
In contrast the Japanese government recognizes about four indigenous races.