Taxonomic Classification of the Human Society

The evolution of human society can be seen through increases in hierarchical stratification.

For instance: a hundred years ago, there were children and adults across different social classes (okay, I'm obviously oversimplifying. If you would like to spend the time creating a full-blown chart, be my guest) On a national level, there were states and colonies. In biology, organisms were categorized into kingdoms, phyla, etc. down to species. (Look up Linnaeus if you really need specifics; I don't.)

Today: there are kids of elementary school, middle school, high school. Teenagers/young adults. College students. Working adults. Retired adults. There is the United Nations, there are/were blocs, trade agreements, states, city-states, territories.... Biology is still reeling from the creation of superkingdoms, a new kingdom, and overhauls at many levels of the original system.

The complexity of society increases, not to a point where we are aware of it, but if we consider the past, it is definite. How inevitable is this process? How inevitable does it have to be? (Having read Tocqueville and Marx, I do dislike the idea that anything must occur. Democracy is not a natural progression for an undeveloped country and Marxist communism hasn't happened yet.)

ore importantly, why is ambiguity so bad? Why can't people be identified simply by what they do? I know there are plenty of arguments against social classes and the caste system, but they had this one advantage: they defined people based on their actions, which affected their positions in society (and vice versa--thank you, established social orders).

But then again, maybe we are an ambiguous society; our functions are multitudinous and social mobility is relatively enormous. Maybe it's so easy for us to change what we do--there are so many options nowadays, after all--that these old systems are simply invalidated.

Either way, I dislike the narrowing of categories as the amount of categories increases. It's frustrating and makes it harder to gain a more general fame in anything except maybe entertainment (but, speaking as someone who didn't know Drew Barrymore was a female in sixth grade, I'm not sure how universal even entertainment really is).