Shazam! star Zachary Levi is set to play former NFL star Kurt Warner in the inspirational sports drama American Underdog from Lionsgate and the Erwin brothers' Kingdom Story Company, it was announced Wednesday. Jon Erwin and Andrew Erwin will direct from a script credited to David Aaron Cohen (Friday Night Lights), Jon Gunn (I Still Believe) and Jon Erwin. The Erwin brothers will produce with Kevin Downes and Mark Ciardi, the latter of whom is no stranger to sports movies, having produced Invincible and The Rookie. Kurt and Brenda Warner will co-produce the film, which is based on interviews …