I don't think I've ever heard anyone describe Keanu Reaves as a "great artist". Quite the opposite in fact. Most charitably, he's a decent character actor who does really well in certain roles that suit him well, but outside of those, he is not a great actor. He also allegedly plays bass in a band decently well, though again is no world-class master of the instrument.
But yeah, he's generally acknowledged as a really nice guy, and also easy to work with.
Weird Al Yankovic, too, is not generally considered a "great artist". A funny musician who made a career making silly parody songs a few decades ago, sure, but that's not what I'd call a "great artist". Again, not to denigrate his work; it was pretty funny stuff as I recall, but nothing super-amazing.
By contrast, people who are generally considered the very top of their profession frequently have serious personality problems. Kevin Spacey was considered one of the best actors in Hollywood, and look what happened to him. Tom Cruise is generally considered one of the most talented actors of all time, and while he's amazing on-screen, he's a certifiable crackpot and mouthpiece for a dangerous cult. Klaus Kinski was also an extremely talented actor, and also extremely mentally ill and unstable.
I skipped Dolly because I honestly don't know enough about country music to know if she's a "great artist" or merely "famous over a long time". Same for the other guy: I'm just not familiar. But I called out your choice of Keanu because it's really well-known that he is not a great actor, and he probably agrees. But it's great that he made a good career for himself anyway; as I said, he does well in certain roles that fit him well. I don't consider myself the top 1% in my profession either.
Of course, I guess this could easily veer off into a discussion about what qualifies as "great artist". Does a top-selling musician/singer who has limited range or uses autotune count, or does someone with amazing technical ability but little commercial success not count? Does a "wooden" actor qualify as a "greater artist" if they've grossed higher than Daniel Day Lewis?
But yeah, he's generally acknowledged as a really nice guy, and also easy to work with.
Weird Al Yankovic, too, is not generally considered a "great artist". A funny musician who made a career making silly parody songs a few decades ago, sure, but that's not what I'd call a "great artist". Again, not to denigrate his work; it was pretty funny stuff as I recall, but nothing super-amazing.
By contrast, people who are generally considered the very top of their profession frequently have serious personality problems. Kevin Spacey was considered one of the best actors in Hollywood, and look what happened to him. Tom Cruise is generally considered one of the most talented actors of all time, and while he's amazing on-screen, he's a certifiable crackpot and mouthpiece for a dangerous cult. Klaus Kinski was also an extremely talented actor, and also extremely mentally ill and unstable.