I think most view life as inherently valuable and that's the default position and the reason for that is emotional. Besides that, people generally view killing as unpleasant. So to reverse that, there needs to be a motivation for killing that trumps the general reticence and a description or characterisation which evoke emotions that surpass the feelings of desiring to avoid conflict or hurting people. One method used to devalue the lives of a group has aimed at characterising them as a threat which must be extinguished. Alternatively, rather than a threat, characterising a group as inferior and justifying that which was otherwise convenient like slavery.

I don't think there's any objective value to life, it's pretty much the strong do what they want and we're both the dominant species on Earth as well as naturally inclined to care through things such as empathy and desires for fairness, at least enough people are like that even if many aren't.

The value of human lifes is not solely dependant on when a killing is considered lawful. That there is no blanket ban in killing doesn't imply that some human lifes are judged to have no value.

For the time being, death is not something we can completely prevent. Nor are we able to avoid clashes of different lifes that can only be resolved by death. This starts at how we fund doctors and hospitals and ends with intentional killing in self-defense. When we ascribe absolute value to human lifes, we do not mean that life needs to be preserved absolutely. Rather, what we mean is that the interests of individuals are to be given equal weight.

That's what differentiates general rules around abortion and self-defense from slavery or genocide.

As to where this value comes from: it's based on every individual's recognition of the other as their equal and mirror.

When once a certain class of people has been placed by the temporal and spiritual authorities outside the ranks of those whose life has value, then nothing comes more naturally to men than murder.
Simone Weil

We know for example that a human fetus has no value and it is its mother which determines if it lives or dies. Society has laws deciding which lives have value in executions for example. A genocide is defined by one collective asserting another has no value so easily destroyed.

Is there such a thing as objective value independent of societal dictates? If so, what is it? What gives life value? — Nikolas

First of all, how do we define life? A mother determines if a human foetus lives or dies because for what she must undertake to maintain the quality of both lives, the mother must perceive, connect and be willing to collaborate with value/potential in that life, even if no-one else does.

I don’t think there is an objective value to anything. But I do think that perception of potential gives life value, regardless of societal dictates.

Death is that which gives life value. Life has meaning because it is limited and ultimately ends. Eliminate death (if it were possible) and create a living hell.