It might help to take a closer look at LeBron's Finals performances, since that's the biggest knock against him:
2007: Lost 0-4 to the Spurs: I don't really hold this one against him because his Cavs teammates were not very good and that team shouldn't have been in the Finals in the first place. But it's worth noting LeBron played poorly in that series, shooting only 36%.
2011: Lost 2-4 to the Mavs: A subpar series for him in which he averaged only 17.8 points/game and lost to a less talented team. A major stain on his resume. There is no excusing this.
2012: Won 4-1 against the Thunder: A great series for LeBron and a well-deserved Finals MVP.
2013: Won 4-3 against the Spurs: More strong play from LeBron to help his team overcome a 3-2 series deficit. Of course, he benefitted greatly from Ray Allen's big shot at the end of Game 6 that tied the game and sent it into overtime. If Chris Bosh doesn't get that rebound, and if Allen doesn't make that shot, LeBron's looking at a third Finals loss in his fourth appearance.
2014: Lost 4-1 to the Spurs. Mind you, Tim Duncan was 37 at the time, and Ginobili was 36. The Finals MVP was a young Kawhi Leonard. LeBron had a great series but it wasn't enough.
2015: Lost 2-4 to the Warriors. Not LeBron's fault at all. Love missed the whole series, and Irving missed most of it.
2016: Won 4-3 against the Warriors. LeBron's signature series in which they came back from a 3-1 deficit against a 73-win team. Legendary stuff. Many people try to discredit this win saying it was because of Draymond's suspension. I don't buy that. The Warriors had Draymond for Game 6 and Game 7, with Game 7 at home. No excuses. Game 7 was when LeBron had The Block. Spectacular play. I was genuinely happy for him and the city of Cleveland. Just remember that it was Kyrie Irving who hit the championship-winning shot.
2017: Lost 1-4 to the KD super team Warriors. No shame in that. LeBron played well but KD matched him bucket for bucket.
2018: Lost 0-4 to the KD super team Warriors. Irving missed the whole series. No Irving, no chance. This was also the series where JR Smith made that huge gaffe at the end of regulation in Game 1, which cost the Cavs the win. LeBron had played out of his mind, and I felt bad for him. You could see his spirit deflate on the bench waiting for overtime to start.
2020: Won 4-2 against the Heat: Many people put an asterisk on this one because of the Bubble, but I don't. Mental toughness is a thing, and LeBron showed it. It's worth noting that the Heat were the weakest Finals team LeBron faced. They only went 44-29 in the regular season, and they were a 5 seed. If you're going to excuse LeBron for losing to the KD super team Warriors, then maybe you should acknowledge that the 2020 Heat were a rather mediocre team.
So it's a very mixed record. He played well in most of those series, but played poorly in 2007 and 2011. At least 3 of those losses are very understandable and not LeBron's fault because of injuries and/or inferior teammates. Those are balanced out by the wins where he clearly had the superior talent on his side as well as the wins where his teammates hit huge shots. He got outplayed by Tony Parker (2007) and Dirk Nowitzki (2011), and he was matched by KD (2017 and 2018). So that's 4 series where he was not definitively the best player on the floor.
Overall, LeBron has had an excellent career, and he's clearly one of the best to ever touch a basketball, but his Finals record is too mixed to consider him the GOAT. Despite being on a super team for 8 consecutive years, he only came away with 3 championships in that span. That's just not enough to declare him better than Jordan. There can only be one GOAT, and that's Jordan.