Here is the thing: I am a southerner-meaning, I was born and bread in the deep south of the US. The 'N' word surely was coined in the south by slave owners/bigots/racists. It is a word that is far more offensive than any cuss word, and in my circle of people in the US, it is never uttered. So, it is strange to hear it tossed into the banter of everyday discourse.
The other night while sitting with family, I was surprised when a cousin, who is a doctor educated in the UK, say, "Well when X is ready to get married, he prefers n-----s"! Oh, my gosh! I almost spit my tea out all over her designer clothing!
As it happens, I began to ask other non-Americans in and around the family, and they also have used that word to simply mean a person of African origin. Shocking! How terrible what the US truly exports to the world! I am assuming that it comes simply from people listening to rap music and just mimicking that. But honestly, I fear for any person to travel to the US and use that word and not get the crap beat out of him or her.
Let me add one caveat: There are still people who still use that word casually in their circle of friends, but they are probably wearing white sheets over their heads and burning crosses in the evenings too.