To assign purpose to a life that ultimately defines its purpose and is thus open to thousands of permutations of purposes seems trivial and exists merely as an ego defense mechanism. Because one man could easily believe his life has meaning if he is contributing to the cause of man while the other believes there is meaning in the pursuit of happiness itself. This very possibility of disagreement points out no absolute meaning of life and thus lacks a definition at all because any and all meanings are valid because we have no almighty omniscient being who exists out of the human experience and inherent bias to judge if what we believe is valid or not. In a world where all meanings are valid: none of them are.
What I is that life itself doesn't have any other inborn meaning than to perish away at a continuous rate, it would actually negate lives meaning. "When there is no other certainty in life than to die it must be it's purpose." this is my stance on this matter, thank you.
You may be a person who keeps contributing to human civilization and live forever at the same time. You can also be a freeloader who lives forever. So it basically depends on how you are and what you want to do. Not all peoples' lives would be meaningless if they were able to live forever.
A life that is 30 years long is just as precious as a life that is 1,000,000 years long. The meaningfulness of the life is merited by how one lives it. It is not the numbers that matter, it is the way you live each day. I personally would accept life-extension technology for myself. I would love to live for millions of years. DE