They aren't universally so, even among current, unmodified humans (e.g., not for me, not for many people I know on different levels, not for many people whose books, papers, and articles I've read, etc.), which is more or less my point. Not all of this can be realistically discounted as selection bias.

Or, to put it another way, the life of a human would hold equal weight for me regardless of whether their birth had been natural, surgically aided or some other value of "artificial".