In literature, the competent man (or peak-human) is a stock character who exhibits a very wide range of abilities and knowledge, making him a form of polymath. While not the first to use such a character type, the heroes and heroines of Robert A. Heinlein's fiction (with Jubal Harshaw being a prime example) generally have a wide range of abilities, and one of Heinlein's characters, Lazarus Long, gives a wide summary of requirements:

A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyse a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.

The competent man, more often than not, is written without explaining how he achieved his wide range of skills and abilities. When such characters are young, there is often not much explanation as to how they acquired so many skills at an early age.