Its pretty simple really. There is plenty of evidence that "LIfe" is intrinsically valuable. Such as the Declarations, Treaties and laws of most countries protecting life as intrinsically valuable. Like how all ethical theories refer to some sort of intrinsic values. Like with Natural Law which is widely acepted. Like with HUman Rights being unalienable.
You're mixing up propositions. These are two distinct propositions:
People value X
People ought to value X
You want to prove that "All people ought to value life" by using the fact that "Some people value life". Okay, let's see that in an argument:
P1 Some people value life
C All people ought to value life
Mmmm... Nope, doesn't follow. If that was a valid argument, then this is an equally valid argument:
P1 Some people do not value life
C All people ought not value life
But in truth, neither of these are valid arguments.
Do not say that "All people value life" because you know that to be untrue.
Do not say that "Most people value life" because that's an argument from popularity fallacy. The number of people who believe something to be true has no bearing on the truth of that thing.
Do not say that "Most people value life
a lot" because that's an argument from emotion fallacy. How strongly people feel about a proposition has no bearing on the truth of that thing.
Just understand that your reasoning is a flat-out non-sequitur fallacy.