Like most of the early Disney movies this has a strong episodic feel to it, but in this case this works for the movie, instead of against it. To some degree it has elements of a coming-of-age narrative, only that this stage is never reached. But Arthur as the young teen getting life lessons from Merlin and his owl is both highly amusing (when the lessons go wrong) and educational (often not for the reason Merlin expected) as well as gives great insight into the characters.
Each of the episodes gives Arthur glimpses of the wider world beyond what he has been exposed to in his mundane existence, and what might be if only he allowed himself to take a step, believe he can fly or dive as a fish. But as Merlin says from early on, he’s cheating. It’s not so much that Arthur is exposed to another path his life could take, but what Merlin is doing is broadening his horizon to the extend that Arthur probably couldn’t shy away from the wider world. The moment he accepted the lessons from Merlin, being a simple squire wasn’t his fate anymore.
The ending on the other hand is just odd. Not sure how the book on which this is based handled it, but in the movie it feels like the narrative does a large deus ex machina (given that this is Arthur it was expected but it still feels out of character for the way the narrative was going, not Arthur himself) and then stops at the oddest point in terms of pacing. But otherwise its quite a fine movie.