There are basically four kinds of jobs:
1)Super - Essential jobs that we all need to live in an area. Specifically jobs that provide food, water, heat, clothing, etc. At one point in time, ALL jobs were that. But long ago we filled all those jobs and we honestly have not increased them significantly. Few people get them anymore.
2)Essential jobs that would cause some but not all people to die if we stopped. Sewer worker, doctors, firemen, cops, soldiers. There are again a limited number of such jobs but occasionally we come up with new "essential' jobs - new types of doctors, pollution monitors/reductions, etc. Most developed countries have filled these jobs, but in certain locations they are unfilled. Why? Because of monetary issues.
3) Supportive jobs. These jobs help the rest of society do their work. Teachers, engineers, manufacturers, etc. They consist of the majority of our jobs and we are no where near the limit. We quite honestly do not have enough money to pay for all the supportive jobs we need. The old and the autistic need help (not prison - nor a prison that is called help). The jobs might have a limit, but we can't see it.
4) Luxury jobs. This includes both research and pleasure producing jobs. They make people happy and more importantly, CREATE NEW JOBS. There is no limit to these jobs and there never will be one. There will always be room for more scientists and more musicians.