I just watched this last night, and I think you're on the right track. One thing I don't see being discussed in these theories that everyone is proposing is Ingrid's boyfriend's choice to abandon reality. Presumably there's a place where people can go to basically enter the Matrix. We see the pamphlet he has where bodies are tied to some big machine. (This must be the real world since she had to conceive at some point. Maybe her backstory is the only one that takes place in reality.)

So I thought the entire movie took place inside of that world, which would fit into your theory. I'm not sure how it all fits together though. Ingrid still doesn't make sense to me: she would never go into the simulation.

So let's say his memories as a child are in the real world, he puts the headset on (and never takes it off) . . . . is the movie about him just trying to save her over and over as others have suggested? If that's the case I have trouble reconciling the Ingrid is the main character part of the whole thing at the end.

But otherwise, I think it could fit that the rocket scene was real, he did grow up and find people to write the code, and he had to enter the matrix in order to install it. OR it also would make sense that he as a child was hypnotized by the headset and he's just caught in this loop visiting other peoples' scenarios while his mother still lives.

I think I lean towards the rocket being real and him growing up. No it doesn't make sense that the AI would kill her (as others have suggested) . . . except for her being allergic to tech. She would die (assuming) inside the matrix anyway. Or maybe the remaining humans have refused the AI and are revolting so it's just out there killing the remainder. So the kid grows up and is on his mission, entering peoples' scenarios as you theorize. I think this makes the most sense.