You ask some good questions for thought.
I am wondering if the birth of Jesus through the virgin can be considered the ONLY time in history that God was manifested as a "son of man" when remembering such a time that God manifested as a flesh man to Abraham and ate a meal with him, and also remembering that "son of man" was a title used of the second person of the trinity long before the birth through a virgin (Daniel 7:13).
		
		
	 
 
I would offer phrase "son of man "used multiple times"  like "daughters of man", speaks of non-converted mankind that must be born again 
of God, in 
Christ, the one
 spiritual seed .
All prophets are addressed a sons of men or daughters of men (flesh and blood) 
Ezekiel 30:2 Son of man, 
prophesy and say, Thus saith the Lord God; Howl ye, Woe worth the day!
Ezekiel 32:2 Son of man,
 take upa lamentation for Pharaoh king of Egypt, and say unto him, Thou art like a young lion ofthe nations, and thou art as a whale in the seas: and thou camest forth with thy rivers, and troubledst the waters with thy feet, and fouledst their rivers.
Ezekiel 33:2 Son of man, 
speak to the children of thy people, and say unto them, When I bring the sword upon a land, if the people of the land take a man of their coasts, and set him for their watchman
The proper use of the word "virgin" has caused much confusion??? Who is the biological father gives birth to flesh if not  Joseph. 
Below, Jesus the son of man the prophet did not say Joseph was not the biological father.   The emphasize is not on his first fleshly birth dying flesh and blood  .Flesh give birth to flesh 
John 6:42-44 And they said, Is not this Jesus, the son of 
Joseph, 
whose father and mother 
we know? how is it then that he saith, I came down from heaven? Jesus therefore answered and said unto them, Murmur not among yourselves. No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day.
 
Catholicism has turned the "virgin birth"  and made it all about sex denying Joseph the biological father in order to crown the demon (spirit entity) they call Mary.  Named after our 
born again sister in the lord 
In that way taking the true meaning of 
virgin as to how it is used . . .away . 
 Timothy is considered a chaste virgin bride (one that has not fornificated with other gods. Violating the 1st commandment . 
 Like the legion of what a Catholics must call patron saints 3,520 and rising his and hers gods in the likeness of men  
2 Corinthians 11:2 For I am jealous over you with godly jealousy: for I have espoused you to 
one husband, that I may present 
you as a 
chaste virgin to 
Christ.
Christian the 
bride of Christ our husband  as the 
mother of
 us all.. 
Revelation 12King James Version12 And there appeared a great wonder in heaven; a 
woman clothed with the sun, and the moon under 
her feet, and upon 
her head a crown of twelve stars: And 
she being with 
child cried,
 travailing in birth, and pained to be delivered.
Galatians 4:19 My little children, of whom
 I travail in 
birth again until 
Christ be 
formed in
 you,