Langston Hughes was among the first to call himself black in 1922

Evidence

The forms of expression were narrative, and most of the time they fit into the folk traditions relating to African forebears, drawing their origins from the history of slavery. A shift in the vocabulary used is also detected: in 1922, in one of his poems, Langston Hughes was one of the first to introduce the word black to describe his identity. — David Theo Goldberg, John Solomos, A Companion to Racial and Ethnic Studies, 2880