My thoughts:
I really love how the movie uses the IRL history of Miles Morale's Spiderman run to add a metatextual element to the story we are being told.
On screen, the story we are told is about an infinite multi-verse of worlds, each holding their own variation of Peter Parker, and each Peter Parker going through the same story with slight variations. Each "Canon Event" is something that has to happen or else the world ends.
Miles, therefore, is an anomaly because his world already had a Spiderman. Peter Parker already went through all his canon events, and that means Miles Morales is not bound by them. He is free to live his own story, and in doing so show the rest of the Spidermen that they can too.
And I love how this comments on the IRL history of Miles Morales and Spiderman AU comics in general.
Because there are a lot of different variations on the story of Spiderman. There's the cartoons, there's AU's, there's reboots. Millions of variations all telling the same story. And we have all these variations because these stories sell. Fans will always line up to read a new cover of "Spiderman's Greatest Hits". But that guaranteed audience also straightjackets the creators writing those stories. If Spider-Gwen misses a "Canon Event" then the comic can lose readers who came to the comic looking to read the same familiar story. And if too many of them leave then the comic might be cancelled.
And so IRL, every missed canon event represents a chance of the comic being cancelled, its world destroyed.
But Miles Morales? Out of all the hundreds of thousands of alternate Spider-men, he is the only one who wasn't written as an AU. It was a continuation. He was introduced to comics after Ultimate Spiderman had just wrapped up one of the most successful retellings of the Spider-man story. Peter Parker's death and Miles Morale's taking on the mantle were an acknowledgement that Ultimate Spider-man's story was over and that it was time to tell new stories.
And it sold like fucking gangbusters. Miles Morales is so popular that when his universe was destroyed Marvel Editorial had him moved to the main universe so they could keep selling his comic.
Miles Morales is the original anomaly. Not an AU, but a continuation and proof both in the movie and in real life that Spider-men don't need to be straightjacketed by the original's story.