You're right, there is certainly nothing in our evolutionary history to suggest that "working all day" is a natural human way of being.

Pretty sure a lot of people worked all day. The difference is they probably slept all night as well.

Pretty sure absolutely none of the "primitive" tribes work all day..

I don't think you have to go back that far. Before electric (and maybe gas lighting) it would be hard to have people working outside of the hours of daylight. Sure you could do some stuff by candlelight but it wasn't cheap if I understand correctly.

This, but unironically

As a scientific word, work all day is unavoidable.

Jobs that co-opt and expropriate outputs of our own work are the problem.