Assuming it was somehow natural or accepted for humans to favor certain humans over others, it would be the is-ought gap fallacy to argue that this is therefore moral behavior.
Such ethical problems are considered in variants of the trolley problem, or the lifeboat dilemma https://en.m.wikipedia.org/wiki/Lifeboat_ethics or similar issues around triaging a group of patients where only a limited number can be saved.
Legally (in many western countries) and morally it is not allowed to prefer people based on gender, race, age, religion, and so on. Typically it is viable to triage in such a way to maximize something like the number of people saved, or eliminate wasted efforts .
However in psychology it is known that humans feel stronger bonds to people with whom they share some properties, and so we "understand" if people make such choices to some degree, even if it remains immoral or illegal. Philosophically there are no reasons why such psychological tendencies should impact moral judgement.