In a life threatening situation where you can save only a limited number of people the ones saved first are always children and women. Why is that the case that children and women lives are worth more ? Is there a reasoning behind this ?
A practical example
You have a ship and not enough life boats to save everybody, your only hope is finding an island to colonize with the survivors...
A: What would be more effective to reproduce? 1: 10 men and 50 women or 2: 50 men and 10 women?
Simply said 1, because 50 women can be pregnant at the same time by 1 man for every 5 women, but 10 woman can't be pregnant at the same time by 10 men each. So to get a larger population in a shorter time the ratio between men and woman is best in favor of women.
B: Able to survive without aid is something that can happen. An adult man would be more likely to be able to survive swimming to shore then let's say a 9 year old girl so by saving the girl you might end up having both while saving the man will at best only give you him. Also the people doing the saving usually survive as well allowing them to teach the young lings while older people will be more stagnant and unable to learn new skills (compared to children seeing they are able to adapt faster/better)
C: (Cultural) Honor, some cultures like the Germanic one for example believe that honor is their entry in to a good afterlife and also that it's a man's duty to protect their women so there is no "downside" in this scenario. While other men just feel like it's their duty out of personal reasons.
Higher level reasoning is not needed here.
You treated people as 3 categories viz., men, women and children. But for a moment you forgot that children include boys and girls.
Among these 3, men are comparatively stronger and so capable to save themselves. When we save children we are saving the next generation. So we give first importance to children's lives in such situations.
Another reason is related to their innocence. When we compare these three categories children are more innocent than the other two. So less chance for a threat. These last two reasons, though you may find it negligible/nonsense, also affect as a motive force.