It wasn't exactly surprising when Superman came back to life mid-way through Justice League, because everyone knew he would. The studio shouldn't have even bothered to try and keep it on the lowdown, it was that obvious.
So, yes, Superman is back in the canon... and he's here to stay, apparently. In one of the last shots of Justice League, after all, we're briefly shown Superman dressed in his Clark Kent guise, returning to work at the Daily Planet.
Wait, what? As if the whole Superman/Clark Kent alter ego thing didn't already make no sense in this era of YouTube and social media, Kent is just going to go back to work to resume his old job, despite the fact that he's reported dead?
No matter how you look at this, it's incredibly iffy. Maybe he revealed his identity, you say? C'mon, it's unlikely Kent revealed his identify to the public and then went back to work as a lowly newspaper reporter with everyone knowing that he's Superman. Essentially, this shot means Superman and Clark Kent return to the world at the same time, in a freak coincidence, despite the fact they look identical.
"Suspension of disbelief" is an understatement, and another sign that the filmmakers have no respect for the universe they're supposed to be building.