Before you claim something, please just spend some of your time to investigate about it. Shape your life yourself, use your own brain instead of repeating samethings told by others just because of its OK with your expectations. So you "want" to have a word in Quran that insult black people and you copy-paste anything as long as it fits with your expectations, without searching about it.
The word which you try to give a meaning as "negro" is Arabic word "abd". It have nothing with black people or negro or something black or whatever, even it does not exactly mean "slave" as its translated in English.
"Abd" mostly used for persons who devotes their life in the way of Islam, who worships to Allah, who devotes their life to Allah, so its a term mostly used to describe Muslims.
Do you have any other questions ?