Why is it said that the Gospel of Luke presents Jesus as "the Son of Man"? It is said that the Gospel of Luke presents Jesus as "the Son of Man"--not the Christ or King or God Incarnate, but distinctively the Son of Man.  

What is it in the Gospel of Luke that gives rise to this particular distinction.  Why is this assertion made and what is the basis of that statement?
The Bible says that Jesus became man, and that He remained being God.
John 1:14 "And the Word became flesh"
Colossians 2:9 "For in Him all the fullness of Deity dwells in bodily form".

So He is 100% human and 100% God. One person with two natures, and one of them, Son of Man.

This does not mean that he has a sinful human nature. Because His father is God and not man after all.
John 8:42 "Jesus said to them, 'If God were your Father, you would love me, for I came from God and I am here. I came not of my own accord, but he sent me.' "