I saw the newest Disney version of "The Jungle Book" in the company of my enthralled 12-year-old son, and there were moments when I envied him—but not too many, because the film is so surefooted in its effects, so precise and simple in its characterizations, and so clear about what it’s trying to say about the relationship between humanity and nature, that it made me feel about his age again, too. Maybe younger.