I didn’t find that to be the case at all. In the beginning it was ok but once the days and shifts start to blend into a large unmemorable mess of tedium my mental state very quickly made me find other lines of work. I couldn’t shake the feeling that I’m wasting my time away as some kind of a almost literal cog.

Some manual labor you actually produce somewhat unique things in the end but some you just do the same thing every day and nothing ever changes or matters in any way.

Exactly. When you do this sort of work, your mind can wander. Compare to programming where you can't get anywhere if your mind wanders.

Of course it's hard on your body and it pays a lot worse.