I'd say Gandalf is probably more like the dm self insert NPC that does exactly enough to move the story where it needs to go. He doesn't use most of his spells because he wants the players to be the ones affecting change. And he suffers from the balrog because the party rolled low on the situation they were supposed to get out of. And Gandalf comes back because the dm said so and it made for an epic twist.

The main supporting parts of that are that Gandalf is the avatar of a Maia, which is kind of like a meta character already. Sort of like having a god in disguise. Not something a dm would allow for a player. As well as gandalfs explicit goal to not be the the pivotal being affecting change, but to push other major actors into doing it.

And lastly, the piece of trivia that Gandalf wasn't supposed to play a bigger role in the hobbit (which came before lotr was written as an epic sequel, and was mostly a story for his kids) than basically a bumbling old sarcastic wizard, brings the concept that the dm just called back a character from a previous campaign.