So... someone help me because I'm so confused now. Is Aquaman played by Jason Mamoa cannon? Is this just them throwing out what was left of the Snyder-Verse shoots?
Not certain what is meant by canon. Not sure exactly who Zack Snyder patterned Jason Momoa's character after but it is more like what was seen both before the
Crisis of Infinite Earths (back in the mid-80s) and after the
New 52 (which started at the beginning of the last decade).
He differs somewhat from the Curry seen between those two DC Comics reboots, the guy with the hook/sword for a hand, in paperback and animated series like
Justice League. He is not the Orin shown more recently in the animated movie and series
Flashpoint and
Young Justice, respectively.
Snyder initially introduced Momoa's Curry in
Batman v. Superman: Dawn of Justice as a brief cameo and was also seen in
Joss Whedon's Justice League, Peacemaker (shadow cameo), The Flash (super brief cameo), and, of course, his first solo movie and Zack Snyder's
Justice League. Not sure what you may have seen so far, which is why I used spoiler masks.
The December movie is all-new with no re-shoots from Zack Snyder. Production had already started before James Gunn was put in charge of revamping the DCU.
How Momoa and his sequel may fit in the new DCU is a question mark. Snyder cornerstones Henry Cavill and Gal Gadot have already been discarded. The same may happen to him. I think the likelihood is extremely high.