Then children were brought to him that he might lay his hands on them and pray. The disciples rebuked them, but Jesus said, "Let the children come to me, and do not prevent them; for the kingdom of heaven belongs to such as these." After he placed his hands on them, he went away. (Mt 19:13-15)
The disciples, in this scene, represent the group which works against the children. There are people who do not like children and who consider children as burden and nuisance and keep them away from their busy schedule. Their running around, their noise, their freedom, their happiness at all times, their sense of wonder, etc make a busy person gets angry. Busy person does not want to be disturbed.
Jesus, in this scene, stand for those who welcome the children whatever they be. He is preaching an inclusive role which welcomes all. Not only he accepts the children as they are but he is also willing to receive them in whatever situation he himself might be. He does not restrict or be controlled by the situation in which he is caught up.
And Jesus prefers this option. Option for the children (also). He also gives the reason for his option because the kingdom belongs to such. Children are open, happy, free, fell equal, and they marvel at creation etc. Such qualities are important in the kingdom and the kingdom cultivates such qualities. Kingdom is the place where one feels happy, free, equal, marvel and all that makes one positive.