Rickson Gracie has over 400 plus fights undefeated 
He has devoted his entire life to Jiu Jitsu.
He was the champion of the whole gracie family they changed martial arts
He entered his first competition when he was six years old and was teaching Jiu Jitsu by the time he was fifteen.
Yes he is a unique individual and so was his father , his father seen love as a weakness so only had kids just to teach them the martial art he created that he called gracie Jiu Jitsu 
The Gracie family teaches now teaches Jiu Jitsu all over the world.
Yes the UFC was the first platform used to show the use of Jiu jitsu
Some of the greatest UFC champions have been black belts in Jiu Jitsu.
Correct, it is a must now in MMA that if you want to be a fighter you should learn Jiu Jitsu as one of the main priority's
It is amazing that smaller fighters have been able to defeat much larger fighters by using only Jiu Jitsu.