Nothing but trollbait in this thread.
Adam Morrison won two NBA championships while all-time greats like Barkley and Malone won nothing. Championships are a nice accolade but are not necessarily essential to a person's greatness. A lot of the time it's a right place, right time sort of methodology. There are tons of great football players who never win a championship, and lots of scrubs that do, so it doesn't really mean as much when you already have incredible numbers. Is Dan Marino one of the greatest QBs of all time? Yes, does he have a ring? No.
Duncan is the best PF of all time because of the win percentages of this team since he got on board. He's a two-time league MVP, 3-time Finals MVP, and don't forget that he's still playing today with consistent numbers despite age and playing time cut down.
Also consider this, the San Antonio Spurs franchise was pretty mediocre to horrible before the 1997 season, even with David Robinson (another Hall of Famer who "never repeated"). Duncan put this team into the echelon of elite NBA teams (only about 5 are in the league) by being an essential anchor to 4 championship teams over multiple generations.
Quit the Kobe vs. Duncan arguments and Spurs vs. Lakers nonsense, I loved the rivalry back then, but it's definitely pretty much nonexistent now. I won't say Kobe isn't great because Jordan has better numbers and more les, nor will I say LeBron is better than Kobe because of his numbers (and his ring count is lower than Duncan's ATM)