Hebrew Scripture clearly tells us that God is not a man, and that He is ONE God, alone.
Numbers 23:19
God is not a man, else he might lie,
neither is God the Son of Man, else he might change his mind.
Has he said, and shall not do?
or has he spoken, and shall not make it so?
Hosea 11:9
I will not execute the fierceness of mine anger,
I will not return to destroy Ephraim: for I [am] God, and not man;
the Holy One in the midst of thee:
and I will not enter into the city.
According to OT scripture, the messiah was to be annointed by God but not God's equal or part of a trinity. The Jews were told over and over and over again that God is ONE.
Deut: 32: 36-41
36) For their rock is not as our Rock,
even our enemies themselves being judges.
37)For their Vine is of the Vine of Sodom,
and of the fields of Gomorrah.
Their grapes are grapes of gall,
their clusters are bitter!
38) YAHWEH will judge his people, and have compassion...
39) And he shall say, "Where are their gods?
Their 'Rock' in whom they trusted?
40) Those who ate the fat of their sacrifices?
and drank the wine of their Drink offering?
Oh, let them rise up and help you, and be your protection!
41)See now that I myself am 'HE',
and there are no other deities with me."
Zech 14: 1 & 9
1)Behold, the day of YAHWEH comes,
and your plunder shall be divided among you...
9)And YAHWEH shall be king over all the earth on that day,
and 'YAHWEH' shall be his one and only name.
Psalm 83:16-18
16) Fill their faces with shame so that they may seek your name, O YAHWEH.
17) Let them be confounded and troubled forever, and be put to shame, and perish,
18)so that men may know that you, whose name is 'YAHWEH', alone, are the most high over all the earth.
ISAIAH 43:11-12
11) I, yes I, am YAHWEH.
And apart from me there is no other saviour.
12) I have revealed and redeemed and proclaimed.
I did this, and not some other among you."
ISAIAH 45:5-6
I am YAHWEH, and there is no one else,
there is no deity beside me.
I strengthened you, though you did not acknowledge me,
So that they may know,
from the rising of the sun
, and from the west,
that there is no one beside me.
I am YAHWEH, and there is no one else.
Isaiah 45:19-22
19)I have not spoken in secret,
in a dark place of the earth.
I did not say to the descendents of Jacob,
"You seek me in vain",
I, YAHWEH, speak righteousness,
I declare things that are right.
20) Assemble yourselves and come,
draw near together, you who have escaped from the Gentile Nations.
They who set up the wood of their graven image,
and pray to a god that cannot save,
have no knowledge.
21)Tell all, and bring them near.
Yes, let them take counsel together:
Who has declared this from ancient time?
Who has told it from that time?
Have not I, YAHWEH?
And there is no other deity beside me,
a just god and a saviour.
There is no one beside me.
22) Look to me, and be saved,
all the ends of the earth.
For I am YAHWEH, and there is no one else.
Hosea 13:4
Yet I am YAHWEH, your god from the land of Egypt,
and you shall know no god but me,
for there is no saviour beside me.
Numbers 23:19
God is not a man, else he might lie,
neither is God the Son of Man, else he might change his mind.
Has he said, and shall not do?
or has he spoken, and shall not make it so?
Regarding Numbers 23:19 -- can be read differently than you intended: it doesn't say God cannot assume the form of a man, or become incarnate, it merely states that unlike a man God does not lie, nor change His mind (although there are many hints in the OT that He does change his mind and even regrets [!] His decisions).
It's the "Son of Man" that is of interest because, as you know, Jesus is both the Son of God (His generate Word) incarnate as Son of Man.
In Hebrew the term used is "ben adam" (son of man, a descendent of humans starting with the man -- Adam). Of course, Jesus is not a descendent of Adam according to Christian belief but a second Adam, one Who does not break communion with the Father.
The original Greek (the oldest OT source, the Septuagint, 180 BC) simply uses the words "huios anthropou" or simply a son of a human being, which is also consistent with the teaching of the Church and therefore this apparent contradiction is not a contradiction at all.
The New Testament has verses referring to Jesus as God and verses that refer to Him as Man. Thus, the orthodox teaching of the Church was always that He had two natures -- one fully divine and one fully human. Most of the early heresies were regarding His natures (monophysites, etc.).