I don’t follow sports much (never have, probably never will) but I came of age in the 1970s when Ali was making his comeback and it was hard not to be aware of him unless you were living under a rock.
But even then, the media mostly portrayed him as this talented boxer with a huge ego. (Both of which were aspects he indeed had, but which alone were an incomplete picture.)
It was only much later that I became aware of how much an amazing fighter he really was, both inside and outside the ring. He literally gave up the best years he could have had in his career as a professional boxer for his principles, principles that were based on fighting for a better world for the oppressed.
It’s a commitment to personal honor exceptionally rare in this world. (The only comparable example I can think of is Paul Robeson.)
Yes, he was in a sport that is now looked down on (in part because of outcomes like the early-onset Parkinson’s disease that Ali himself eventually succumbed to). Yes, in his early years he aligned themselves with the Nation of Islam and embraced their sometimes hateful rhetoric.
That just makes him a real person with real-world flaws who still achieved the greatness he did, which just makes me admire him all the more.