Here's what Affleck told EW regarding Batman and the Justice League -
“Batman represents human beings, mortal men. In a world of Flashes and Aquamen and Supermen, there needs to be that guy. It’s interesting that he became the leader of the Justice League in the books – I’m not sure how that will play out here – but his humanity is also an asset.”Screen Rant has the full story below.
Batman V Superman: Ben Affleck Talks Justice League Leadership Role