"The Son of Man", Jesus' favorite designation of himself, in view of Numbers 23:19-20? (This question has been closed though OP rephrased it.I will risk asking it rephrased again):

Given this quote from Numbers 23:18&ndash;20


  Then he took up his discourse and said, "Arise, O Balak, and hear; Give ear to me, O son of Zippor! God is not a man, that He should lie, Nor a son of man, that He should repent; Has He said, and will He not do it? Or has He spoken, and will He not make it good? Behold, I have received a command to bless; When He has blessed, then I cannot revoke it." 


Given Jesus used the title the "Son of Man", to refer to himself, 81 times in the Greek text of the four Canonical gospels. For example, he asked his disciples: "who do men say that I, the Son of Man, am?" (Matthew 16:13). Given this expression "the Son of Man" is used only in the sayings of Jesus. 

The question is (in view of no consensus&mdash;agreed upon single&mdash;interpretation of this phrase, "the Son of Man", has emerged despite almost two centuries of Christology):


What are the reasons for this disagreement on interpreting Jesus' favorite designation of himself (despite the plain words of both Jesus and Numbers 23:19-20)?
What are the major Christological interpretations of this designation "the Son of Man" and what are their biblical bases?


Thank you very much (please do not close).
Since I was the OP of the original question I believe the following is a partial answer.First of all, I totally disagree with the frequent denial of historical Jesus.

The answer of  @the dark wanderer, "the most common answer to your question is that what you have found is just another Biblical indication of The Mystery of Faith (i.e. the Trinity)", reflects the Christological perspective of what is called Pauline Christianity ( not in a derogate way here) or Trinitarian Christianity as apposed to Unitarian Christianity.

Pauline Christianity perspective on the phrase Son of man is that it is, I gather, a possible affirmation of Jesus humanity as the title Son of God affirms his divinity. Jesus as the Son of God is essential to Trinitarian Christian creed since the first century AD. In contrast, Jesus as the Son of man was never part of Trinitarian Christianity creed.

That is said, in the Hebrew Bible the expression "son of man" (בן–אדם, ben-'adam) also appears  far more times.
The use of the article the in "the Son of man" in the Koine Greek of the Christian canonical four gospels is not found in any old Greek documents . Geza Vermes says the  Christian canonical four gospels usage "the" son of man is not found in the Hebrew Bible , suggesting that the term origin is Aramaic ברנש, bar nash/bar nasha. He concludes that " in these sources "Son of man" is a regular expression for man in general and often serves as an indefinite pronoun and in none of the extant texts does "son of man" figure as a title." jewishencyclopedia elaborates:

"Among Jews the term "son of man" was not used as the specific title of the Messiah. The New Testament expression ὅ ὑιὸς τοῦ ἀνθρόπου is a translation of the Aramaic "bar nasha," and as such could have been understood only as the substitute for a personal pronoun, or as emphasizing the human qualities of those to whom it is applied. That the term does not appear in any of the epistles ascribed to Paul is significant. Psalm viii. 5-7 is quoted in Ḥeb. ii. 6 as referring to Jesus, but outside the Gospels, Acts vii. 56 is the only verse in the New Testament in which the title is employed; and here it may be a free translation of the Aramaic for "a man," or it may have been adopted from Luke xxii. 69. n the Gospels the title occurs eighty-one times. Most of the recent writers (among them being II. Lietzmann) have come to the conclusion that Jesus, speaking Aramaic, could never have designated himself as the "son of man" in a Messianic, mystic sense, because the Aramaic term never implied this meaning. Greek translators coined the phrase, which then led, under the influence of Dan. vii. 13 and the Logos gospel, to the theological construction of the title which is basic to the Christology of the Church." 

But still I don't feel I have a satisfactory answer to my original answer and of course yours.This why it is important not to hasten to close questions.This way we will never learn anything.

For farther readings:

Christian Theology: An Introduction by Alister E. McGrath (2010) 

Addendum: @the dark wanderer statement "docetism hasn't been resurrected as modern heresy for a while, those Muslims commit a modified form of this heresy in saying that Christ was never really crucified, he just created an illusion that appeared to be" is a misstatement based on misunderstanding of both Decetism and Islamic creed about Jesus Christ. Muslims do not say that Jesus Christ made it appear he was crucified.They say 'they slew him not for certain', i.e. he did not die in the cross for certain (that is at least my understanding).