Funny thing is, most of the Gracie's I have watched and read about are not really mixed martial artists either. Which is why Royce came to a point in his career that he was also finished. BJJ is really great at one mode of fighting. But people who are all grappling can't contend in MMA anymore then people who are all striking. Not anymore anyway.
Studying Bruce's life as a martial artist, there are several things I think he contributed.
When he refused to be told that he could not teach people who were not asian, they eventually sent someone to his school to fight him. He barely won using his traditional Kung Fu. That lead him to looking into alternatives. (This fight did not happen in some buddhist looking temple from Mortal Kombat like you see in the movie "Dragon: The Bruce Lee Story" but there was a fight that he fought because of that situation.)
When he was standing up in front of a lot of martial artists trying to inform them that the classical "fancy mess" was making martial arts ineffective someone did charge up and challenge him. Witnesses to that exchange said he finished the guy with grappling. That points to MMA.
Ironically his movie career did contribute to it as well as after the success of "The big boss" (Fists of Fury) a rival movie company offered a million dollar movie contract to anyone who could defeat him in hand to hand combat. This lead to people showing up at his home and challenging him constantly. He eventually got a bodyguard just because he could not even get anything done in a given day.
One story that was shared with me was the day a guy jumped over his back fence while he was playing with his kids in the backyard so that he could try to cash in on the movie contract offer. His bodyguard got up to handle it and Bruce asked him to sit down as he was going to make an example out of this guy who frightened his children. And that's what he did.
While he was making "Enter the Dragon" a similar thing happened. And witnesses said that he finished the guy by grappling with him in such a way that allowed him to take the guy by the head and smash it against one of the stone walls on the set until he got the message that he needed to cut it out.
So the reason for Lee's innovations and evolutions were because of discovering the real world limitations of his classical style, including the need for better ground fighting skills. And because of that there is a full ground fighting curriculum in JKD to this day. (And now it includes BJJ).
So this I feel, is where they get the idea that he could be called the "father of MMA".
Take a look for example at the stuff being taught at this school. Jun Fan is his "modernized" version of Wing Chun. Muay Thai, and a mixed grappling regime. I visited this school before UFC 1 even happened and they were already teaching ground fighting as an essential part of self defense. (Scroll down to the schedule).
It's very nice of you to give us insight into all the things you're wrong about.
The real father of modern MMA
Gene Lebell vs Milo Savage happened in 1963 years before Bruce Lee died in 1973.
You will PM me about it and we will both share a hearty laugh. Which we won't, because we're going to be cyborgs and incapable of feeling emotions anymore. But still.