Depends on what you meant by worth.
You start out as carbon, you end up as carbon.
-Principle of Conservation of Matter
That is a person's CHEMICAL worth.
Now, if you were referring to moral worth, that is where the conflict will start, for I believe that humans define morality. I will give you my view of moral worth.
To state it clearly, I will give an analogy.
It is no different from economic worth. For example, in Japan, rice is more expensive than meat. In Japan, rice is "expensive". Compare that to the rice:meat price ratio here in the Philippines. In the Philippines, rice is "inexpensive". Having said that, how are people able to brand "expensive" and "inexpensive"?. That is, through a standard.
(I don't have exact figures, but even if my assumed values are incorrect, I'm trying to point out something else here.)
Now let us turn to morality. It is undeniable that killing is tolerable in other countries. In some countries, people even eat babies. Now, how does one judge the moral worth of actions? Why, through a standard, of course. Let us assume the view of Christianity, for example. To Christians, the act of killing is "immoral", therefore it has negative moral worth. That mere branding of "moral" and "immoral" is a way of defining. And there is my point--humans define moral worth. And another point I was trying to make is that morality is relative.
(The flaw in this analogy would probably be the fact that economics is an exact science and morality is not quantifiable. But basically, my point here is that humans brand things with respect to a standard, hence the relativity.)
Sure, you can say that other factors affect worth.
In economics:
-resource
-geography
-demands
-etc.
In morality:
-religion
-culture
-social norms
-etc.
But how would that address the argument that it is humans who define morality?
Before I completely deviate from the topic, my final statement would be:
Humans are chemically nothing more than carbon, but Humans can define their worth.
