Why had a very young child been chosen as part of the mission?

A very young child was chosen as part of the mission primarily because they could resist the Whisperer due to their stubbornness. The child’s natural inclination to be persistent and defy influence is crucial in the context of the narrative. The Whisperer is a manipulative entity that affects the thoughts and behaviors of individuals, especially targeting those who are more susceptible to suggestion. Young children, through their inherent characteristics and strong will, can often resist such coercive tactics effectively. This resistance is vital for the success of the mission, making the child's stubbornness an important asset.

While creativity, problem-solving skills, and personality are all valuable traits, they are secondary to the specific need for someone who can withstand the psychological pressures imposed by the Whisperer. The mission requires members who are not easily swayed, and a stubborn attitude in young children makes them uniquely qualified for this challenge.