I am not sure where the idea of creating different levels of black belt came from, although I am aware that Prof Jigoro Kano did promote some to 10th Dan grade in his life time. So, perhaps that also was an invention of Prof Kano. Any one know the true story behind Dan Grades?...
My understanding is that the 1st-10th dan rank system was borrowed from the game Go, which, much like chess, has a ranking system for players.