Boy — Applied by white racists to imply that the individual was less than a fully functioning, responsible citizen.
Negro —Scientific description, like Caucasian. Eventually considered to be demeaning and replaced (although Caucasian stuck around).
Colored — An excellent descriptor given the actual diversity of color and the technical inaccuracy of “black”, but eventually considered demeaning and replaced, except by the NAACP.
Black — A passable descriptor, like “white”. Proudly asserted by many, yet not immune from causing offense with those predisposed to be offended.
African-American — A truly PC invention, yet understandable and mainly descriptive, given the use of Italian-American, German-American, etc. However, the latter terms had almost totally dropped out of common usage (after the mass immigration generations had passed), making African-American stand out as a forced term. Unlike Asian-American, which is commonly shortened to just Asian, “African” is considered to be a highly offensive descriptor. This is probably due to the original forced nature of the term.
Urban youth/teenager — Applied by white racists to imply that the individual is less than a fully functioning, responsible citizen.
Here’s a new one, much more descriptive useful and... scientific:
Africanus Americanus— a sub species of feral negro humanoids descended from urban humans, who have developed in norms of unsocialized wild conditions, genetically altered by chemical ingestion of street narcotics and home creations (with names like “lean” and “purple drank”). Behaviours exhibited include random and planned acts of violence usually conducted by pairs of the species against targeted older individuals, with a higher incidence of actions against vulnerable Caucasians of any age, including infants.