Why does Jesus use a child as our model of discipleship? It is because in a child is the absence of duplicity. What you see in a child is what is there. There is no pretense. 

A child sees the world through the lens of simplicity, treasuring things that are meaningful. This simplicity is seen in the awe and wonder of a child’s mind. They see beauty and goodness in things that adults pass over as insignificant. Their seemingly, humanly, undeveloped minds are more in tune with reality than many adults because of their simplicity. That is why Jesus stated unless we become like little children we cannot enter into the kingdom of heaven.

Adults tend to clutter their lives with many possessions, none of which will be theirs after death. The child is content with a few things which do not possess him/her.

This simplicity of the disciple of Christ reflects a heart in right order, keeping first things first. The first thing is the Lordship of Jesus before anything else.  As a result, life is seen as a journey, not to rush through to the next destination, but to enjoy the flowers on the way. It is in the present moment that the will of God is revealed and embraced. This takes simplicity.