"Our understanding of the world is built up of innumerable layers. Each layer is worth exploring, as long as we do not forget that it is one of many. Knowing all there is to know about one layer -- a most unlikely event -- would not teach us much about the rest." -- Erwin Chagraff
Consider the oft-despised termite. The obvious 'individual' is the little bug you see crawling around in your wall, obviously 'separate and distinct' from all of the other little bugs. (Yes, I know this is not the technical usage of 'bug'.)
But, for many purposes, it turns out, the real unit of analysis should be the colony, which, in many ways, functions as a super-organism with, for instance, one reproductive organ (the queen), one nervous system, and so on. Or, glancing in the other direction, the 'individual' termite itself appears as a colony, made up of the insect and numerous mixotricha paradoxa (and other symbiotes) occupying the insect's gut and enabling it to live on wood, which the insect, by itself, cannot digest. Now, surely those little guys are indisputably 'individuals', right?
Well, they were called 'paradoxa' because Sutherland, the woman who discovered them, was puzzled that these protists seemed to have both cilia and flagella, which had never been seen on the same critter before. ('Critter' is the correct technical term here, I believe.) Well, they turned out to be stranger than she thought -- the thousands of tiny 'cilia' were discovered each to be 'individual' bacteria symbiotes -- and where cilia usually 'plug in' to a protist at a basal structure in the cell wall, the 'oarsmen bacteria' turned out to be anchored to yet another bacterium!
Anyway, the point of all of this is that sometimes, when looking at termites, the 'right' level of analysis will be the species. Sometimes, the 'right' level will be the colony. Sometimes, it will be the 'apparent' individual, the termite. Sometimes, it will be the termite as itself an ecosystem. And sometimes it will be the components of the termite ecosystem as themselves ecosystems.
Why, other than the desire of economists for simplified analysis or libertarians for a dunk-shot justification of their preferred political policies, should we expect social analysis to be any different? Why would social analysis display one uniquely 'right' level of analysis?