Who is "The Death of the Last Black Man ..." Old Man River Jordan from The America Play, and Other Works and what is their importance?

I'm not sure about the death of a black man as a character. Black Man and Black Woman are the central characters in "The Death of the Last Black Man in the Whole Entire World." Both are identified not by name, but by degrading socio-cultural stereotypes associated with African Americans - watermelons and fried chicken. These names are clear metaphoric evocations of the social oppression under which, the author contends, African Americans all live, to one degree or another.