Beginnings in literature are highly confusing. In media res, inciting incidents, grab-‘em-in-the-first-five-pages-or-I-can’t-represent-this… you know the drill.
To back up, I think the easiest way to think about plot is that a story has to ask a question. And then not answer it. And then answer it. If it’s a novel, you might want to have several questions, some of which are answered as they resolve themselves into different and perhaps more difficult questions.
But we are getting ahead of ourselves. In fiction or creative non-fiction, we start with a question. (In prescriptive non-fiction, the equivalent is identifying a lack which the reader perceives within himself or herself). Beginnings ask questions. Good beginnings ask good questions.