I was fine with Batman and WW, but I admit it is starting to get a bit ridiculous having all these other super-powered characters show up in this world so shortly after Superman made his appearance.
Perhaps if the end of the movie were to jump forward in time a few years before they all arrive, the idea would make some kind of sense. But somehow I doubt that's the way it's going to go down.
My guess is that they're going to take the approach that there have been superheroes and otherworldly things around for a while but that they've been below the radar and it's the emergence of Superman that brings them into full public view. And, as Christopher
says, they may introduce some characters in their non-powered form before ramping things up later.