All verses of Scripture will be in harmony if we interpret them in the correct way, and may not harmonise if we interpret them incorrectly. So John 17:5, along with the other verses I mentioned, indicate that Jesus was alive long before his human birth, especially John 8:
56) Your father Abraham rejoiced to see my day: and he saw it, and was glad.
57) Then said the Jews unto him, Thou art not yet fifty years old, and hast thou seen Abraham?
58) Jesus said unto them, Verily, verily, I say unto you, Before Abraham was, I am.
Consider also Hebrews 1 (WEB):
1)
God, having in the past spoken to the fathers through the prophets at many times and in various ways,
2)
has at the end of these days spoken to us by his Son, whom he appointed heir of all things,
through whom also he made the worlds.
3) His Son is the radiance of his glory, the very image of his substance, and upholding all things by the word of his power, who, when he had by himself purified us of our sins, sat down on the right hand of the Majesty on high;
4) having become so much better than the angels, as he has inherited a more excellent name than they have.
5) For to which of the angels did he say at any time, “You are my Son. Today I have become your father?”and again, “I will be to him a Father, and he will be to me a Son?”
6) When he again brings in the firstborn into the world he says, “Let all the angels of God worship him.”
7) Of the angels he says, “Who makes his angels winds, and his servants a flame of fire.”
8) But
of the Son he says, “Your throne, O God, is forever and ever. The scepter of uprightness is the scepter of your Kingdom.
9) You have loved righteousness, and hated iniquity; therefore God, your God, has anointed you with the oil of gladness above your fellows.”
10) And, “
You, Lord, in the beginning, laid the foundation of the earth. The heavens are the works of your hands.
I think your logic has failed in this case! Being with God doesn't mean you are God, no more than the disciples being with Jesus meant that they were all Jesus. As you said in another post:
"but can you tell me how a person who is with someone else, [can] also be the very same person as that someone he/she is with or beside? Yes, it is a logic reasoning question. Is it possible?"