Value of a Person

I have been having slightly philosophical thoughts this week, perhaps because I have been spending so many evenings doing manual work (sewing and building furniture for my eldest's new room). My main "big" train of thought has been how to value a person. Perhaps the question itself is wrong, but modern society compels us to see ourselves in terms of productive value (easiest measured by income). I often like to think that people are valuable in creating better conditions or happiness for those around them. This goes way beyond anything material, and is something I strive to do. Here the value of parents can be more easily measured (beyond the sum of incomes of a cleaner, cook, shopper, interior designer, entertainer, nurse, etc). But what about people like - and this triggered these thoughts of mine originally - the drunk homeless person on the corner of the  street? Surely many of these people have been productive (income wise) and helpful (producing happiness in e.g. their friends and family) before. And surely they are valuable, for some larger reason? Why do we primarily measure ourselves in terms of costs to society, and value we produce? A few simple thoughts on a larger meaning-of-life-size issue.