Two stars. Rated R. 91 minutes. There’s an ongoing argument that runs through much of the movie “Morgan.” Should the title character, a tomboyish slip of a thing in an ever-present hoodie, be referred to as a “she” or an “it”? Living in a glassed-in cage, on the other side of which Morgan’s keepers monitor their young charge — only occasionally entering the cell for a brief interview — the movie’s apparently teenage protagonist opens the story with a jolt: by stabbing this odd little zoo’s nutritionist (an under-utilized Jennifer Jason Leigh) in the eye. “Why the heck did she/it do that?” is the film’s central mystery.