The first hip hop song to be a radio hit samples "Good Times" by Chic pretty heavily, so much so that Nile Rodgers and Bernard Edwards sued for songwriting credits. The song, ironically, started when the Sugarhill Gang and Fab Five Freddy JOINED Chic on stage and came up with an impromptu rhyme to go along with the LIVE bassline of this song.
That wasn't the only sample they used. "Here Comes That Sound Again" by Love De-Luxe was also sampled. Did Alan Hankshaw get a songwriting credit? Noooooooooo.
More importantly, this was the song that brought hip hop to a broad audience. No, it wasn't the first, but it was the first hit. It would go on to be one of the most influential one-hit wonders in history.