This is one of the most accurate generalizations that you make here...and the irony is that you used three examples of progress in science to illustrate postmodernism!

What you don't really unpack here is that the overly idealistic notions of the logical positivists (whose position most closely resembles what you characterize here as "modernism", at least to my eye) didn't represent the end of that train of thought. The difficulties exposed by those results--and philosophical arguments--resulted in a different sort of abandoning of modernism for a flavor with reduced certainty. One can track this thread through Popper and Kuhn and Quine, and see it appear in the compact yet powerful characterizations of science given by people like Carl Sagan, Richard Feynmann, and Neil deGrasse Tyson. The insight that the truth about many things really can't be known definitively was accepted, incorporated, and used to make the whole endeavor of understanding objective reality more effective.

At the same time, alas, despite having some good points, the critical theorists and structuralists and so on became increasingly possessed by Descartes' demon, dragging themselves and society down into less and less reality-based approaches, while continually generating interesting enough ideas, challenging other approaches in insightful enough ways, to not immediately be discarded as purveyors of nonsensical nihilism.

Anyway, the result is that there are a lot of people--scientists, for instance--who don't fit either of your characterizations well at all. For instance, they may not believe in the sanctity of cultural traditions at all if the evidence is that a particular tradition causes problems, and yet, they don't embrace a struggle between narratives as good for understanding much of anything except how people tell competing stories and some tend to be accepted more than others (sometimes contrary to objective facts).