But the productiveness of Labour pales into insignificance compared to the productiveness of Capital (defined as Property) and NEITHER is independently "productive".)

Under technologized conditions, the power of dead labor (i.e labor-saving technology) appears to dwarf that of living labor (i.e. the individuals operating that technology).  What one doesn't see, in a cursory observation of the modern factory, is the labor that went into creating the labor-saving technology.  Marx counts that, too, in his reckoning of the productivity of labor.

Sure, nature is "productive," too, but not in the sense that it is someone's "property."  Property, as Locke asserted two-and-a-half centuries ago, is a person's legal relationship to a thing.  Now, the Nature Conservancy might own a chunk of "property" for the sake of keeping it out of production altogether, and thus said "nature" would not be productive altogether.

I don't see why it's necessary to take the terms of the Labor Theory of Value, mix them around a bit, change their definitions here and there, and re-present it as a whole new defense of socialism.

"Imagine all the people/ Sharing all the world" -- John Lennon