Why does Jesus refer to himself as the “Son of Man”?

Question

Why does Jesus refer to himself as the "Son of Man"? This is similar to Why does Jesus speak of himself in the third person?, but I am specifically looking for an explanation of the "Son of Man" references.

Answer 1

From "The Dictionary of Jesus and the Gospels"

Thus: “When E. Hiyya ben Adda died … R. Levi received his valuables. This was because his teacher used to say: ‘The disciple of bar nāšâ is as dear to him as his son.’ ” Here the expression plainly refers to the group of teachers

It is suggested that the idiom was used as a form of self-reference in cases where the speaker wished to show modesty or to speak of matters (such as his own death) which were distasteful—in any case in sayings where he wished to avoid speaking directly in the first person. --Green, J. B., McKnight, S., & Marshall, I. H. (1992). Dictionary of Jesus and the Gospels (779). Downers Grove, Ill.: InterVarsity Press.

There are several theories about what Jesus was alluding to in calling himself son of Man (literally son of 'a-dam'):

1. A re-affimation of his authority to forgive sin (which entered via Adam).
2. An allusion to the suffering that he will undergo
3. A kindredness that will be evident at his return, in which he will come not just as a conqueror, but as a redeemer who is coming (back) to his own.
4. An allusion to his Messianic role, since the Messiah would be "the Son of Man"
5. A reference to the inheritor of the world, per Daniel 7. The last beast to have authority was "like a Son of Man"

With any of these motives, by speaking of himself in the third person, he is making an audacious claim (the power!) but couching it in the most humble terms he can.

Answer 2

He was alluding that he would fulfill the prophecy made by the Prophet Daniel in Daniel 7.

13 “In my vision at night I looked, and there before me was one like a son of man,[a] coming with the clouds of heaven. He approached the Ancient of Days and was led into his presence. 14 He was given authority, glory and sovereign power; all nations and peoples of every language worshiped him. His dominion is an everlasting dominion that will not pass away, and his kingdom is one that will never be destroyed.

It was as direct a claim of messiah ship a first century Jew could make. The Jews understood this and is why he was so widely held as a blasphemer by the Jewish people. This is further reiterated by passages like

Mark 2:10

New International Version (©1984) But that you may know that the Son
of Man has authority on earth to forgive sins..." He said to the
paralytic,

The Jews understood that only God had the power to forgive sin. We even have a passage where his disciples admit that he is the messiah.

Luke 9

Peter Declares That Jesus Is the Messiah 18 Once when Jesus was praying in private and his disciples were with him, he asked them, “Who do the crowds say I am?”

19 They replied, “Some say John the Baptist; others say Elijah; and still others, that one of the prophets of long ago has come back to life.”

20 “But what about you?” he asked. “Who do you say I am?”

Peter answered, “God’s Messiah.”

Answer 3

I have heard that it is a mystery why Jesus referred to Himself as the Son of Man. And yet it was in fact what Jesus called Himself the most.

I see it like this, Jesus is speaking as God, because He is God. His perspective on everything is from the point of view of God. So what makes Jesus unique foremost, is not that He is a man who is God, but rather that He is God, but also a man. In all the Universe, here is God as "the Son of Man (mankind)". Or - I am God and also a man, not I am a man who is also God.