A cursory google search gave me no information on the origins of this saying “one of a kind”, so I feel free to offer my own interpretation. And, of course, it is contrary to the common understanding, which is “in a class of its own, unique etc.” That rendering fits in with our overdetermination to develop, secure, and defend our ego driven sense of individuality. I am more inclined to understand this use of the word “kind” as a derivative coming from the cluster of ” kin and kindred.” The dictionary supports the notion of unique, but seems to keep it within the class of which it is a member. Of course, that makes sense, but we seem to resist any suggestion that even while none of us have the same face nor finger print, we do have different sets of commonalities and can in fact be understood as “typical” in certain ways.
Perhaps the most humbling, yet useful understanding available to us, once we accept it, is that our personalities can be experienced as reflecting certain types of behavior. Humbling because it seems to “rob” us of our prized individuality. Useful because it provides us with a path towards effective communication. Confusion and conflict often result from taking as a personal injury, that which is more likely the unintended automatic reflection of a typical response, all be it, not the one we wanted. Sometimes the hardest thing to keep in mind, is that it is not always all about us. And the corollary, that not all misunderstandings have to generate our daily drama.