Yeah, Star Wars canon is… interesting, cause there’s layers of canon, like an onion. A canon onion. Not to be confused with an onion cannon, which just sounds like fun and a lawsuit waiting to happen.
Basically, first you have G-Canon, anything George Lucas says or makes, which is in theory “more” canon than anything he says or makes before. Hence, the prequels and the OT movies are canon (though, from what I understand, the Droids and Ewoks cartoons might be as well). Then there is N canon, which is the novels, and some other kind of canon before you have the mixing pot of everythign else, including games and stuff like that, which is canon if absolutley nothing else contradicts it.
IIRC, Star Trek is much simpler in terms of canon: “Voyager, Enterprise, and Star Trek 5 didn’t happen.”
As someone who’s never read any of the EU stuff or any novelizations of any kind I’ll also concur that there’s a lot of the prequel trilogy that was considered to be common knowledge well before the movies were even hinted at.
Within my geeky group of friends it was common knowledge that Vader was born when Anakin was driven into a volcanic lava flow in a saber battle with Obi-Wan. It was then told that it occurred on something of a rock bridge over the flow with Obi-Wan knocking him in.
It was common knowledge that the Emperor and the clones killed off most of the Jedi.
It was common knowledge that Boba Fett was a clone, though it didn’t quite capture the whole story as told in the movies.
There were a lot of stories about the origins and cultures of the various aliens presented, little of which was shown in the movies except the Wookie planet.
I think much of this was taken from the stories and definitions that often appeared on the boxes the toys and figurines came in.
As far as I’m concerned, the only canon is The Star Wars Holiday Special. Even the original Star Wars is somewhat suspect, in that it fails to provide a balanced perspective to the events on Tattooine. And it’s been well established that Ben Kenobi was lying out his ass through the whole film.
And I don’t trust any little green puppet-men. Nope, only the Holiday Special can be considered an objective view of the Star Wars universe.
Although most of the stories are very fuzzy to me now, the Star Wars Marvel comics series had some wacky aliens newly introduced to the star wars Universe (I think there was a green rabbit man, in one of the stories) and the story lines seemed to be all over the place. They were very interesting stories but just barely within Lucasian History and definitely outside of his sensibilities.
Here is an übergeek reference to the “canon” at the time of the filming of the movie-formerly-known-as-Star-Wars-full-stop:
The trouble with Lucas and the concept of “canon” is there’s really no such thing until it’s in the can. There’s nothing wrong with that, in principle. Lucas, however, had a habit of making out like there was this Tolkienesque creation lurking in notebooks somewhere just waiting to be revealed, whereas the reality is he pretty much made it up on the fly, as the quote above, and the attrocious prequels, clearly demonstrate.
I also remember reading that the original concept had Luke first defeating Vader relatively early in the story arc, growing as a Jedi to eventually confront the Emperor for some epic one-on-one in the climax. Lucas then ditched the idea before filming TESB for the “I am your father!” angle, upsetting one of his collaborators so much he quit in disgust.
I seem to recall (as a big SW nerd) that the whole Volcano story came out of some movie magazine around the time predating ESB. Obi-Wan and Vader were battling and Vader ended up taking a swim in the lava.
As for the OP, what was ‘canon’ in the SW-verse was, IIRC, “Anything not directly contradicted by the movies.” Which is how Fett managed to get several origin stories - it was never covered in the movies, so they’d never gotten contradicted.