Try this: do you think an individual invented the term "black", or an individual invented its application to dark skinned human beings, and everybody else over an entire continent and two centuries - who had never thought of such a thing for themselves - learned to do that from that one guy? Does that make sense to you as a likely historical account of what actually happened?
It was the Spanish colonists who applied the adjective
negro, literally "black" (pronounced NEH-groh), to the African slaves, for the obvious reason that to their eyes they looked quite black. In Spanish, adjectives can be used as nouns when applied to humans, so the people became
negros.
The people of the British colonies (which eventually became the USA) borrowed the word, but pronounced the word according to English phonetics and it came out NEE-grow, and as is standard in our language, it was only used as a noun. In the South, where the colonists came from regions in England with different accents, it was mangled into "NIG-ger." No insult was implied, it was just a matter of phonetics.
When it became necessary to distinguish the slaves from their masters, the people of European ancestry were called "white," which is obviously the opposite of black/
negro.
It was't until after the Civil War, when the people of the now-defeated Southern states regarded the now-freed slaves as the root of their problems (rather than their medieval storybook economy with the white people as the aristocrats and the black people as the yeomen, since white people were no longer willing to be yeomen), that "nigger" came to be used primarily an insult, rather than just a descriptive term.
A linguistic chess game ensued as old words became taboo and new ones replaced them. The phrase "colored people" was coined in 1909 by W.E.B. DuBois and the other founders of the "National Association for the Advancement of Colored People," and this was the term regarded as polite by "white" people up through the 1950s.
Then the "colored people" decided to simply call themselves "black" and we had come back to the beginning of the circle.
But after a couple of centuries of intermarriage (or more likely rape), many of the people in the "black" community didn't look much darker than the "white" people, so the term "African-American" and its more easily pronounced variant "Afro-American" came into vogue.
The term I used originally, and ever since, is "white men". Same term, page one to page eight. It's the term they used for themselves, all the millions of them, and - as you repeatedly emphasized - it's practical.
But after WWII, when racism began to wane--every so slowly--intermarriage among the people of European ancestry and all of the other immigrant communities (Latino, Eastern Asian and Western Asian as well as African and Native American) left us without any good names for a huge segment of the population.
The children of immigrants (or slaves or people whose ancestors were here before ours arrived) tend to grab onto an identity, and commonly call themselves Latino, African, etc. But the next generation--which generally intermarry with little regard for race--usually identify themselves simply as "Americans," just like the rest of us.