I would say "It's fiction", but that might be akin to walking into a church and saying there's no God.
I used to buy into this geek-culture notion that for every fictional universe there must be one factual interpretation of it called 'Canon'. But there's really no way to reconcile that with the fact that all the good fictional universe has been written by so many different people with such drastically different creative visions that there's no real thematic consistency. So now I just pick the creative vision I think makes the universe most interesting.
And isn't the origin of the word 'Canon' the body of writings that the Roman Catholic church has declared and selected to count as legitimate holy writings? The use of the word to describe the factual truth of fictional universes is a little bit ironic.