I've read a couple of books recently which assert that one's protagonist should be shown in his normal, everyday life BEFORE the inciting incident. This is to empower the reader to understand and sympathize with one's protagonist. Maybe there's some merit to that. However, I don't understand how to apply it in my current WIP. My story begins with an amnesiac older boy, the protagonist, waking up from a coma. His normal life exists before he enters the coma. No one knows who he is and no family claim him. He apparently survives a plane crash. Much later in the plot, the reader discovers that the boy is a space alien and his UFO crashed into a plane. How can I squeeze his normal life into the first fifty pages?
Don't force something where it doesn't belong. The "normal life before the inciting incident" thing is formula. Which doesn't mean it's bad. It just means it's formula. Just like having the hero hit his/her low point at the end of the second act. There's a place for it, and then there are places where it doesn't belong. It sounds like your story benefits from the "normal" life being kept hidden and slowly revealed over time. That's a perfectly valid way of doing it, too. Keep storytelling strategies like these in mind, absolutely. But don't feel beholden to them. As for whether or not it'll work...write it and let some beta readers tell you if you've pulled it off or not. That's what they're for.
I agree, this isn't something you should force in where it doesn't belong, and clearly it doesn't belong in your story. Ignore it.
Jason Bourne was depicted exactly this way in The Bourne Identity. The back story is revealed slowly as the story progresses. You feel empathy for him not because of his back story but because he can't remember it.
Squeezing his WHOLE before life into the first 50 pages along with his current situation would be turn into an info dump. ddavidv example of The Bourne Identity is a good one. Fragments of flashbacks triggered by scents, places, situations will give readers the sense of the understory.
You could have a brief flashback before he wakes up, as a prologue or the beginning of the scene, that depicts some of his previous life. Perhaps a warm moment with his family. If he is not obviously an alien, then the memory could be designed to not give that away. Perhaps his family settled on earth as fake humans? That would require alteration of the coma explanation but I think it would be worth it. Especially since the UFO feels potentially corny/cliche and this could help explain why no-one noticed he is not human. He'd need a physical hiding method because of DNA tests and such. Anyway, if that flashback is his first experience, it would be a good way to direct his quest. After all, he needs a thread to follow at some point.
Always be aware that there is no right answer to this question. I know this doesn't apply to your situation, but look at The Martian, both book and movie. In the movie, the inciting event - the storm that seems to claim the life of Mark Watney - takes place in the first scene. In the novel, this scene doesn't take place until halfway through - it's a flashback; the first scene is actually a log entry from Mark Watney describing his current, post-crisis situation. It's the same story, but handled in two different ways, and both work just fine.
Yeah, this occurred to me, too. If he's in a coma in a medical setting, they will have taken bloods, done all sorts of tests on him. Unless he matches humans in this kind of thing, there will be a lot of suspicion awaiting him upon his awakening.
