Kareem Abdul-Jabbar and LeBron James are both all-time greats, and most people would consider them in their top-5 players ever. Both players have won multiple championships and multiple MVP awards, and there are definitely people who believe that each of them has a case for being the GOAT of basketball.
Detroit Pistons legend Isiah Thomas seems to believe that, and he has recently called Kareem Abdul-Jabbar and LeBron James "the two GOATs". However, he omitted Michael Jordan from his Tweet, which drew anger from a lot of fans who roasted him for hating on Jordan.
While Kareem Abdul-Jabbar and LeBron James are both viewed as the GOAT by groups of fans, the majority of the public would agree that Michael Jordan is the GOAT. Abdul-Jabbar and James may get some points for their longevity in the game. Both played at a high level for an extremely long time. But neither Kareem Abdul-Jabbar nor LeBron James managed to get two separate three-peats like Michael Jordan.
Isiah Thomas and Michael Jordan notably had a huge rivalry in their playing days. Thomas has even previously claimed that it is a fact that he was better than Jordan and dominated him. While Isiah Thomas does have a winning record against Michael Jordan, there's no question that Michael Jordan was the superior player. That isn't a slight to Isiah Thomas: he is a legendary point guard, and one of the only people that beat Michael Jordan, Larry Bird, and Magic Johnson in their primes.
We'll see if Isiah Thomas changes his mind on the GOAT debate in the future. Like any other person, he is entitled to his opinion on this matter. The GOAT debate will never truly end, as fans generally all have different opinions. At the end of the day though, Kareem Abdul-Jabbar, LeBron James, and Michael Jordan are all fantastic players, who deserve to be recognized as the GOATs of their respective eras.