I think the term canon has been misused.
Checking my dictionary, it says, "A member of the chapter of a cathedral or collegiate church"...oh, wait, that's the second...The first is about laws, but the third bit seems most relevant, "The list of an author's works which are accepted as genuine; the Shakesperian
canon."
Looks like we gotta go to TV Tropes. [www.tvtropes.org/pmwiki/pmwiki.php/Main/SarcasmMode]Not that I ever go there or have memorized the URL or anything.[/url]
The page for TV Tropes on canon defines it as "[t]hat which counts, in terms of continuity." It goes on to be more specific for specific definitions in literature and television, but not video games.
I think that canon for DF can be classified into three categories, in order of decreasing importance: 1.
Word of Toady. 2. What happens in-game. 3. How things are clearly stated to be in the raws*. In none of those locations has it been clearly stated what, exactly, the player is. Therefore, any speculation is
non-canon. The only possible exception is if the note in Legends Mode that the adventurer was possessed by strange forces or whatnot counts as Type 2 canon for the theory that the player is Armok or somesuch.
Anyways...yeah.
*Allowing things like "The melting point of adamantine is 25,000 degrees Urist" to be canon.