What concerns me is I don't think you understand what you are saying.
I repeat, the original point was that people generate jobs, not an influx of people, just people, I think I have proved that cannot be correct.
Then you made the point that people, especially of working age move for work which I think is a platitude, a trite or obvious remark.
Finally you made the point that an influx of people moving for work reasons generates more jobs because those people will need things, which is fine except that they have to have money to pay for these mythical things, where are they to get this money?
I am not arguing that there cannot be a sweet spot that an area can benefit by, a aligning of various positive economic factors allowing increasing prosperity. But I don't really believe in "trickle down", I don't believe people on their own create jobs and there are only so many cleaners, nannies, burger flippers that are needed in a developing area, to get more than that they need useful skills to contribute to the regions industries!