The Son of Man

God is not a man, that he should lie, nor the son of man, that he should change his mind. -- Numbers 23:19 (ESV)

The Jews was expecting "the Son of man" be the Messiah (Matthew 17:12), this is also clear when Jesus ask the question:

Now when Jesus came into the district of Caesarea Philippi, he asked his disciples, “Who do people say that the Son of Man is?” -- Matthew 16:13 (ESV)

The Jews were expected a specific "Son of Man" to come which was prophesied.

In Genesis the same Hebrew name that is often translated as "Adam" also means "man".

So God created man in his own image... -- Genesis 1:27 (ESV)

and

The LORD God formed the man of dust from the ground and breathed into his nostrils the breath of life, and the man became a living creature. And the LORD God planted a garden in Eden, in the east, and there he put the man whom he had formed. -- Genesis 2:7-8 (ESV)

and

The LORD God took the man and put him in the garden of Eden to work it and keep it.

And the LORD God commanded the man, saying, “You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.”
Then the LORD God said, “It is not good that the man should be alone; I will make him a helper fit for him.”

Now out of the ground the LORD God had formed every beast of the field and every bird of the heavens and brought them to the man to see what he would call them. And whatever the man called every living creature, that was its name. The man gave names to all livestock and to the birds of the heavens and to every beast of the field. But for Adam (Man) there was not found a helper fit for him. So the LORD God caused a deep sleep to fall upon the man, and while he slept took one of his ribs and closed up its place with flesh. And the rib that the LORD God had taken from the man he made into a woman and brought her to the man.

Then the man said, “This at last is bone of my bones and flesh of my flesh; she shall be called Woman, because she was taken out of Man.”

-- Genesis 2:15-23 (ESV)

The God gave His Word to Eve:

I (God) will put enmity between you (the devil) and the woman (Eve), and between your offspring and her offspring;
He (Jesus) shall bruise your head, and you shall bruise his heel.”

-- Genesis 3:15 (ESV)

God never told Eve that He Himself would personally come and bruise the devil. He promised that Eve's offspring would do that.

Eve was the wife of "Man". So when Jesus says he is the "son of Man" it means he is that promised "offspring" of "Man" that will bruise the head of the "snake".

Everytime when Jesus refer to himself as "the Son of Man", he uses it in the context of his special role or purpose. Just to list a few examples:

But that you may know that the Son of Man has authority on earth to forgive sins -- Matthew 9:6 (ESV)

For the Son of Man is lord of the Sabbath -- Matthew 12:8 (ESV)

For just as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth. -- Matthew 12:40 (ESV)

For the Son of Man is going to come with his angels in the glory of his Father... -- Matthew 16:27 (ESV)

... the Son of Man coming in his kingdom -- Matthew 16:28 (ESV)

And as they were coming down the mountain, Jesus commanded them, “Tell no one the vision, until the Son of Man is raised from the dead.” -- Matthew 17:9 (ESV)

See, we are going up to Jerusalem. And the Son of Man will be delivered over to the chief priests and scribes, and they will condemn him to death...even as the Son of Man came not to be served but to serve, and to give his life as a ransom for many -- Matthew 20:18,28 (ESV)

For as the lightning comes from the east and shines as far as the west, so will be the coming of the Son of Man... then will appear in heaven the sign of the Son of Man, -- Matthew 24:27,30 (ESV)

Therefore you also must be ready, for the Son of Man is coming at an hour you do not expect. -- Matthew 24:44 (ESV)

... and so forth.

Jesus compared to Adam

However, Jesus was not the same type of human as us:

For as by a man (Adam) came death, by a man (Jesus) has come also the resurrection of the dead. -- 1 Corinthians 15:21 (ESV)

For as in Adam all die, so also in Christ shall all be made alive. -- 1 Corinthians 15:22 (ESV)

Thus it is written, “The first man Adam became a living being”; the last Adam became a life-giving spirit. But it is not the spiritual that is first but the natural, and then the spiritual. -- 1 Corinthians 15:45-46 (ESV)

The first man was from the earth, a man of dust; the second man is from heaven. -- 1 Corinthians 15:47 (ESV)

As was the man of dust, so also are those who are of the dust, and as is the man of heaven, so also are those who are of heaven. -- 1 Corinthians 15:48 (ESV)

Just as we have borne the image of the man of dust, we shall also bear the image of the man of heaven. -- 1 Corinthians 15:49 (ESV)

If Jesus was God, it would be unfair to compare a human with Him. Instead, Paul refers to Jesus as "a man".

Although he also states that both Adam and Jesus were different from us:

Adam, who was a type of the one who was to come. -- Romans 5:14 (ESV)

If Jesus is God, then Adam must be a type of God too.

Jesus is not God

The Bible never directly state that Jesus is not God, but instead:

However, it is worth noting that Jesus was also declared "the Son of God" by God Himself.