But my idea of what the basic concept of 10 Cloverfield Lane is, is that the John Goodman character has locked the other characters in the basement "for their own good", and for most of the movie the audience doesn't actually know whether something actually happened out there or not.
Since you haven't seen it yet, I'll spoiler code this. It's just a comment on what you typed, but it is spoilery, so if you'd rather see the movie unspoiled at some point, feel free to skip it.

There was an incident in the movie where someone outside was trying to get into the shelter. If I'm remembering the timeline of the movie correctly, I *think* that was around the halfway mark. It did show the characters (and audience) that *something* was going on out there, just not necessarily *what*.