In German (one of the roots of English) the word for black skinned people is neger. It's pronounced with a short 'e' and rhymes with 'begger'.
Many of the slave ships were Dutch, another Germanic language. It is conceiveable that a word like 'ni*ger' was heard frequently among slavers ... and they weren't all illiterate.
I'd say that wade78 is not cut out to be our histroian, nor our language expert.