One of the most overlooked things about Muhammad Ali (other than his racist quotes that get ignored a lot) was that his greatness and success as a boxer came from three sources.
The first of course being his skill, both mechanical and tactical. His style resembled the great Jack Johnson with perhaps a better KO punch.
The 2nd being his master of the psychology of the game. Often times he had his foe psyched out before or during a fight and that can make the difference in a sport where one must be disciplined. It’s worth noting that the reason why he won his final fight against Frazier is that Frazier quit first, if Frazier had decided to answer that final bell there was every possibility that Ali would not have been able to physically do so.
The 3rd was his promotional ability, both for himself and for individual fights. Both as Cassius Clay and Muhammad Ali he was the master of generating gate, and much of his brash talk was toward that end. While one can make the argument that culturally that had a bad long term impact on sportsmanship there is no doubt that it was effective and given the nature of the sport where one has a finite opportunity to make a big payday completely understandable.
In terms of how he changed the game, promoted the game and dominated the sport of Boxing I think a comparison to Babe Ruth is valid. The only difference being that Ruth is unquestionably the greatest baseball player of all time because he was a Hall of Fame Quality Pitcher as well as one of the most feared hitters in History. With Ali you can make the case for Jack Johnson, Joe Louis, Rocky Marciano, Larry Holmes or Mike Tyson as his equal or better in his division, (and if you consider all divisions the discussion expands) but frankly the difference would be so small as to be meaningless.
No matter what your opinion of Ali the Man, Ali the Boxer was extraordinary athlete who came at exactly the right time (The beginning of the Television Age) where all of his skills were able to shine.
That’s Babe Ruth all over