For decades, Steven Spielberg has been synonymous with the movie business. The filmmaker has created some of the big screen’s most enduring moments, delighting audiences by spinning fantasies involving lovable aliens, menacing dinosaurs and one very hungry shark. And he’s even done the unimaginable and made movies about brutal subjects like the Holocaust and the D-Day landing that find commercial success, as well as critical plaudits. But with “The Fabelmans,” his semi-autobiographical look at growing up as a film-obsessed teenager in Arizona and Northern California, Spielberg is confronting a movie business that is unrecognizable from the one in which he...