But in the USA, where I live, only "Negro" was used in any sort of 'neutral' way. In the South, even today, (though less & less) you will hear those who are pretending not to use THE "N Word", saying "Nigra".
Both forms were clearly meant to affirm the user's disdain/hatred/contempt for a racial/ethnic group, and simply referring to color was seldom in their minds. Most bigots were probably not even aware of the etymology.
It was interesting, being in the college NAACP and watching as the "CP" changed what they wished to be called...from 'colored' or 'Negro' to 'black' to African-American (even those from the West Indies). Now 'black' is sort of back in style...depending.....

I try to respect the wishes of those affected, as far as I can determine it in various contests.