Your entire first argument is built on the premise that a thing either has value, in which case we should never allow its death, or it hasn't, in which case we can allow its death. It denies the existence of any middle state where a thing may be recognized to have some value, but that value may come second-best in a conflict with something of even greater value.
Animal cruelty laws make the opposite case. Clearly, animals are not recognized in our society to have as much value as humans ; we eat them and allow them to be property. Yet, clearly, they are recognized to have some value, since we feel the need to restrict the abilities of their owners to treat them inhumanely.
It seems pretty obvious that human society recognizes intermediary degrees of value, not just a binary choice between "valuable" and "not valuable". Things and beings in those intermediary degrees are often granted some measure of protection, but less than those recognized to have greater value.