Since I don't think even being trained as a world or comparative historian would qualify any of us to answer this question from expertise due the scope and sweep of it, I'll answer it perhaps somewhat indirectly in terms of methodology and theory.

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In short, can this idea be traced back to an original source? No. Is it a unique and universal quality of human nature? Probably not.

Why do I say this? Partly because the idea, as described, is so broad and general. At this level, it is really not a matter for historians to study, it is a question for philosophers and literary critics. All a historian could say is that it is an exceptionally common sentiment in many societies across the broadest span of time and geography possible. Of course, the opposite ideas--that self-preservation is important, that "discretion is the soul of valor", that one is not required to sacrifice one's life for another, are equally common.

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The only way for a historian to grapple with this as a question that could be studied would be to specify it. In a particular time and place, what did a particular society seem to think about the proposition that it is good or desirable for individuals to sacrifice their lives to save another person's life? Who disagreed with that idea? How was it expressed in a particular concrete institution where the likelihood of self-sacrifice seemed more present? (Among soldiers, among people with dangerous jobs, in talking about the death of women in the bearing of children, etc.)

I don't think you can even settle comfortably on the idea that this is a basic facet of human nature. There have been institutions within societies and perhaps even whole communities who have largely or substantially disagreed with this proposition, instead exalting forms of self-preservation. In many societies, this has been at least an active debate or disagreement within institutions and between individuals. And I think many evolutionary psychologists or sociobiologists would argue that some forms of "altruism" of this kind are common in other species, particularly social organisms, and often have to do with degrees of genetic relatedness. (E.g., honey bees sacrifice their lives when they sting a threat to the hive; but they are all half-sisters who are defending their mother, and so their sacrifice nevertheless helps to reproduce their genes.) So maybe it's not even that distinctively human in that respect either.

There are some questions which are very interesting but nevertheless not very historical, at least not at a certain level of generalization and sweep. This is one of them.