> because everyone's "need" is the same. Maybe adjusted by a few exceptions like family size
And the parts of Marx you quote say literally that exact thing: that people's needs vary only depending on whether they are married, how many children they have "and so on and so forth".
In other words Marx didn't recognize any connection between quantity or quality of work and what you get back. In a Marxist system your income is a function of family size. Indeed Marx didn't even recognize the concept of "work smarter not harder" because he believed everyone's work was exactly the same and the only difference was that big strong men could deliver more units of abstract "labor" per hour than a small weedy sick man.
Why do you think your quotes dispute what I said? Is it not perfect support for it?