Literacy is the least important characteristic. though it allows rules to be made and records to be kept, it does not affect the people or the buildings very much.
Medicine is kind of important. Though it does not help with building, it allows people to live instead of dying to a sickness. It also helps them live longer.
Math is the most important characteristic. Though it does not do much for people, it is needed to create buildings and expand the civilization. It can also be used to make maps and be able to go places without being lost.