I haven't read any philosophy classics in well over a decade so I'm a bit rusty but I want to buzzsaw through modern philosophy in order to explain the rise of the normative/descriptive distinction and the fall of the subject/object distinction (which isn't quite dead, I just think it should be).
Start with Descartes, who drew a thick line between subject and object. The subject aligned roughly with what we'd call conscious experience while the object was dead mechanism. The subject was immaterial, the object material. He suggested they met in the pineal gland and somehow, whatever...there was a lot of straw-grasping.
Meanwhile the term subjective came to mean arbitrary and referred to matters of taste and private experience while objective came to mean, roughly, naive realistic straightforward quantifiable things in the world that are what they are, existing apart from the subjects who know about them.
The most obvious problem with Cartesian subjects is they're immaterial and operate outside natural law. Hit a human in the head with a sharp enough object and you'll find they're susceptible to natural law. No pineal gland theory can save you here, Descartes. You said immaterial. Further, it appears at this point in history nothing other than noocentric conceit to think humans operate outside natural law, or are immaterial, at all.
The most obvious problem with naive realistic objectivity is neglect (or in Kant's terms finitude). Cognition systematically neglects information. Abstractions become more powerful when they leave information out. Human vision picks up only a sliver of the light spectrum. Human brains don't have access to what they cognize in the way suggested by the term objective. There is no object in the simple sense intended by Descartes.
Hume famously pointed out that you can't, logically, get from an "is" statement to an "ought" statement. What is and what ought to be is the descriptive/normative distinction. Nietzsche later wrote a brilliant, even by his standards, piece called "Beyond Good and Evil" in which he made the case that there is no "good and evil," only "good and bad." Every time humans claim something is evil, what they really mean is "I don't like it." Hume's ought/is distinction is really a distinction between statements with a built-in good/bad (for the cognizer) element and statements without one.
The terms descriptive and normative are compatible with a materialist approach to the human. Both are simply ways the material brain cognizes. Both are susceptible to bias, presumably the normative more so. Both are subject to natural laws. Both occur in the world. Both neglect information.
Descriptive means "whatever you or I think about its goodness/badnesss, X is the most accurate (leaving aside whether accuracy is good or bad) model of Y. Descriptive is the new objective. The term normative, on the other hand, refers to whether one likes the results of the descriptive process.