Killing another human being of any age is morally wrong and I would apply that to any culture at any time period back to the paleolithic. Our only excuse is that it may sometimes be necessary, but it is still immoral. The problem with any discussion of morals is that people assume that if an immoral act is justified it becomes moral; it does not; it just makes us feel better.
I suggest that the conceptual mind cannot “see” anything unless it is given a label.
I suggest that ultimately there is no such thing as “morals” or “moral behavior”.
The mind of man observes, attaches names and mistakes the names for realities.
It creates a pseudo-reality composed only of adjectives to which it attaches other adjectives.
“Texas” is a description, not a place.