The Rock was casted two years ago
He might as well have been. But I think Levi can pull off the whole 12 yr old in a god's body pretty well.
As far as Justice League being under a shy under 2hrs...im fine with it! We don't always need superhero films to be 2 1/2 hours. The first X-Men was an 1hr and 45 mins, and despite the special effects not up to par to today's standards, it was a well paced film with a lot of characters at play. Moreso than Justice League. Not everyone who wasn't Wolverine, Magneto, or Rogue had a backstory in that film, and if they did, it was enough information to just keep the story going.
I think the MCU has really hammered the "EVERYONE NEEDS THEIR OWN MOVIE" mind set that people are getting too nitpicky about who is going to show up on screen. 17 years ago, people would be losing their minds just to see the Flash on screen. Now people are complaining he's in Justice League because he didn't get a standalone first?? Get outta here