Use value

The physical properties of something that make it useful, as opposed to its abstract ratio to other commodities which is known as exchange value. It then follows that the use-value is limited by its physical properties. Use-values do not always have to be commodities (example: air, tools made in feudalism, etc.). It is also the substance of all wealth.

First part of the paragraph: "Labor is the source of all wealth and all culture."

Labor is not the source of all wealth. Nature is just as much the source of use values (and it is surely of such that material wealth consists!) as labor