in my opinion, life is not priceless, it is valuable though.
why I say this is simply perspective.
reasons:
1 if it was priceless we would stop at nothing to preserve it, which isn't what we do, Africa for example
2 if life was priceless we would all share the common understanding of that ideology, therefore would be much less hate crimes
3 life is meant to be taken, circle of life, the life of the blade of grass is taken to feed the cow, the life of the cow is taken to feed the human.
4 finally we could turn to a terrorist hostage situation. the old " we do not negotiate with tourists" situation, if life was priceless and seen as such that phrase wouldn't exist, because we would bend to anyone to spare a life
I really hope I answered properly, have a great day
