Let's imagine I had 100 rocks. For some reason I have to move them in order to feed everyone.
If I have one person I can move one rock a day.
With two people I can move two rocks.
And so on and so forth.
There is a labor demand - the need to move rocks.
And a labor supply - the number of people you have available to move rocks.
You can't mind game your way out of that. Call it a commodity or not, you still need X people to do Y tasks and the discrepancy between the tasks and the people you have to do them is a measure and very real thing.