By Michael Cavna, The Washington Post It took a cartoon to render a cinematic Batman at his most human. As I continue to talk with fans of “The Lego Batman Movie,” two aspects keep coming up: How this film’s Joker engenders uncommon sympathy, and how moviegoers finally get a relatable Dark Knight. Those elements aren’t unrelated. “Lego Batman” is the most smartly subversive superhero film since last year’s “Deadpool” and goes after more specific game.