Except it isn't. People have different perceptions of moral and immoral, largely shaped by their culture and upbringing. There are many examples where people f

Except it isn't. People have different perceptions of moral and immoral, largely shaped by their culture and upbringing. There are many examples where people from countries or even the same country but a different period of time have wildly different moral values - just consider slavery, war etiquette, polygamy, cannibalism, eating certain kinds of animals, the death penalty, abortion, socialism, welfare state, age of consent, etc... In all of these areas, there any many viewpoints that are seen as abhorrent and immoral by others, yet either were or still are held by others. I wouldn't even say that it's an instinct not to kill other people, as I'd imagine an infant left in the wilderness to fend for itself probably wouldn't regard an encounter with a human any different to any other unfamiliar animal that may or may not want to kill it. If it seems to present a danger, they'd probably avoid them or kill them. If they killed them, that'd also be a source of food, possibly even an easier source of food than what they normally ate. However, we're taught by those around us the societal norms, including not killing others, from a very early age. It's a desire that most people have for acceptance and wanting to fit into a society that leads to following these rules. Sure, if you grow up in the absence of any kind of societal influence, your moral code might just be an instinctual "I must survive", but that's radically different to most people who have ever lived. What about acts of self-sacrifice for a greater purpose? Maybe it's instinctive for mothers to protect their children, but not so much for self-sacrifice to help strangers. Sure, it happens, but only some times, and only by certain types of people. But in any case, who are you to say that the point isn't to probe your value system? That's certainly one of the outcomes of thinking about these questions and questioning why you make certain choices in some situations that you wouldn't in other situations. There's also no way you can say with any certainty that not one single person who has ever posed this kind of question hasn't had the intention to make people think about their own value system.