That question is quite vague. Perhaps you should be more specific.
Lets see if I've got the question right: I'll ask your question to me again.
How is it so that "the Classification system is a human fabrication"?
The answer:
The Biological classification system "is a method of scientific taxonomy used to group and categorize organisms hierarchically."
The "modern biological classification has its root in the work of Carolus Linnaeus, who grouped species according to shared physical characteristics.
Carolus Linnaeus was a human being.
" the idea of the Linnaean taxonomy as translating into a sort of dendrogram of the Animal- and Plant Kingdoms was formulated toward the end of the 18th century"
"With Darwin's theory, a general acceptance that classification should reflect the Darwinian principle of common descent quickly appeared."
"One of the first modern groups tied to fossil ancestors were birds. Using the then newly discovered fossils of Archaeopteryx and Hesperornis, Thomas Henry Huxley pronounced that they had evolved from dinosaurs"
You see, the modern classification system is a "human fabrication" just like I said. It does not occur in nature. It originated in the minds of human beings. It doesn't exist apart from human beings.
Biological classification - Wikipedia, the free encyclopedia