I am most drawn to the idea that we are all individual parts of something larger and are here to learn and grow from our experiences.
We are all then likely to be at different points on this spiritual journey, giving the illusion of different levels of "worth" but at the same time, all having the same potential to grow. Its like comparing a 5 year old schoolchild to a 15 year old; the 15 year old has more intellectual knowledge, but this is not because they are "worth" more than the 5 year old, they have just had more time to learn than the 5 year old. In the same way, the more spiritually evolved people on earth, may seem to have more "worth" but may just have had more time to become who they are.
RE: How valuable is a human life? Are we really all worth the same?!