Are Wages Really Equal to Labor’s Marginal Contribution to Production?

According to modern mainstream economic theory, capital, labor, land, and similar inputs are considered factors of production and each is rewarded according to the marginal contribution it makes to output. From this perspective workers' wages are regarded as fully consistent with their contribution to production.

However I believe there is a problem with this theory. Physical and financial capital themselves (setting land aside for the moment) are also created through labor. In technical terms, a portion of the output produced by workers is exchanged for depreciation, since part of current production is used to maintain and replace the existing capital stock.

Of course a business initially begins with capital provided by the entrepreneur. However, according to studies this initial investment constitutes only a very small fraction of the average existing stock of capital* Most of the capital currently employed in production has been accumulated and reproduced over time through the productive process itself.

To expand the theory further some modern critical theorists argue that is why capital owners do not take risks because the capital is not technically created by them.This part is interesting but not exactly my idea.