The "problem" with many modern jobs is that they're divorced from the fundamental goal, which is one of: 1) Kill/acquire food, 2) Build shelter, or 3) Kill enemies/competitors/predators
The benefit of modern jobs is that they are much more peaceful ways for society to operate, freeing up time for humans to pursue art and other forms of expression.
What he got wrong was that this alienation results from capitalism.
It actually results from civilization. The people who built the pyramids across every continent, for example, performed assembly line-like work. Any large-scale project requires it. And large-scale projects are fundamentally necessary for most societies.
Capitalism was invented in the late 1700s.
I don't think Marx said that worker alienation was specific to capitalism, rather, his work was in describing the economic system of his time, and what that would entail for people living in it.
> It actually results from civilization.
I disagree, I can't think of anyone in Medieval Europe as alienated from their work as a modern sweatshop worker. Not that serfs had it better, but you get me.
Serfs were essentially slaves who had effectively 0 ownership over their output, so I'd strongly disagree with that sentiment.
I think the best argument for a time when there was almost 0 alienation of labor was when we were all hunter gatherers. Where every activity was closely connected to something necessary for survival.
As soon as we built larger societies, greater division of labor became necessary to efficiently support the society. And thus alienation of labor became much more pronounced.