Jesus said that if we don’t accept the kingdom like a child we will not enter the Kingdom of Heaven. What did he mean by this statement?Also, when Jesus called himself Son of Man, what does that mean?
When Jesus says that anyone entering the Kingdom must come into it like a child he is talking about the qualities of child-likeness that make one a better citizen in the Kingdom. Qualities of children which are important in the Kingdom of God include humility, teachableness and willingness to rely on God for both guidance and protection rather than relying on self. Children are also unbiased in the way they treat people. Additionally, they are innocent with regard to certain sins. By the way, there are some qualities of children we should not imitate, such as their lack of wisdom and their selfishness!
As for the phrase Son of Man, this is a fairly enigmatic label compared to Son of God because son of man is applied to Daniel and Ezekiel (as well as to Jesus), whereas Son of God is never applied to any human other than Jesus Christ.
When Jesus is referred to as Son of Man, the humanness of Jesus is being emphasized. Jesus is both Son of God and Son of Man because he is both God and man. He is fully human, yet he is a very special godly human, so he is Son of Man. He is also God-in-the-flesh, and therefore he is Son of God.
It is not completely clear that the distinction I am making is the whole story of why Jesus is sometimes called Son of God and other times Son of Man, but this is the traditional way of viewing the use of the two phrases.