Me:”...the latin adjective “niger” - which meant the color black”
You could easily be right - I tool 7 years of French but no Latin... I did look it up and found numerous references that said “nioger” however.
http://www.ferris.edu/jimcrow/caricature/
>>The etymology of nigger is often traced to the Latin niger, meaning black. The Latin niger became the noun negro (black person) in English, and simply the color black in Spanish and Portuguese. In Early Modern French niger became negre and, later, negress (black woman) was clearly a part of lexical history. One can compare to negre the derogatory nigger – and earlier English variants such as negar, neegar, neger, and niggor – which developed into a parallel lexico-semantic reality in English. It is likely that nigger is a phonetic spelling of the white Southern mispronunciation of Negro. Whatever its origins, by the early 1800s it was firmly established as a denigrative epithet. Almost two centuries later, it remains a chief symbol of white racism.<<