It's reasonable to imagine that there was some sort of "natural selection" of economic systems and that the one that emerged is relatively close to ideal.

That doesn't follow: the crucial thing about natural selection is that, given path-dependence and local optima, it doesn't matter which particular feature causes the "fitness"; only the fact of its total fitness matters, and any given feature could just be a "hanger-on".

Now, if you had numerous worlds (or merely societies) to compare, and a rigorous, well-accpeted definition of what counts as capitalism, and strong selection pressures and "mutuation", then the present content of a system would be strong evidence of the superiority of all of its parts. But that's not the case.

I'm open to suggestions for how I might improve the introduction to the article to make the article more palatable.

You should have dropped the whole pro-capitalist cheerleading and simply discussed the belief that jobs are zero-sum, the evidence that people generally hold this belief, and its errors. (And then discussed how people can be made to change this belief, given their general cognitive structure.)