Your explanation of the two verses in Philippians 2 ignores not only the context of those verses it also ignores what the Greek words mean.
Your NAB explanation is ludicrous especially from a church that claims to have given Christendom the NT. The DRV was translated from the Latin Vulgate and contains that verse so if it was added at some point in time it was added by Jerome or some other minion of the Catholic Church in the 4th century. Also read Mark 4:18-21 where Jesus told the Jews He fulfilled the prophesy concerning God's anointed.
In order to establish the preexistence of Jesus one must rip Scripture apart. However, when we put those Scriptures back into their full Biblical context as well as the cultural background of those God gave the responsibility to receive and transmit His word these Scriptures do not support the preexistence of Jesus. Now as to those two verses you ripped out of context.
John 3:13 reads:
John 3:13
13 "And no one has ascended into heaven, but He who descended from heaven, even the Son of Man. NAS
How did Jews understand “descended from heaven”? Jews viewed God’s blessings as “descending from heaven” or “came down from heaven” or “is from above”. James expresses this Hebrew concept when he wrote:
James 1:17
17 Every good thing bestowed and every perfect gift is from above, coming down from the Father of lights, with whom there is no variation, or shifting shadow. NAS
James 3:15
15 This wisdom is not that which comes down from above, but is earthly, natural, demonic. NAS
Jesus is the predicted prophet born of a woman who existed as God’s predetermined plan and is God’s gift to mankind.
In order to understand the exchanges between the Jews and Jesus we must understand Hebrew thought processes as well as have a working knowledge of the OT, especially the Messianic prophesies. Jesus favorite title for Himself was “Son of Man”.
Daniel 7:13-14
13 "I kept looking in the night visions,
And behold, with the clouds of heaven
One like a Son of Man was coming,
And He came up to the Ancient of Days
And was presented before Him.
14 "And to Him was given dominion,
Glory and a kingdom,
That all the peoples, nations, and men of every language
Might serve Him.
His dominion is an everlasting dominion
Which will not pass away;
And His kingdom is one
Which will not be destroyed. NAS
Now as to John 6:62, the past tense is often used to indicate a future event has already been accomplished. For instance in Psalm 110:1 David views the Messiah as already sitting at the right-hand of the Father, in Revelation John views the future as happening as he watched. What prophets viewed in visions, which “came down” or “descended from above” Jesus was totally aware of and explained not because He preexisted but because of His unique relationship with the Father who bestowed on Jesus all the wisdom, authority, and knowledge He needed to accomplish His assigned task on this earth and in His future reign as the King of kings. All you have done is draw attention to the fact that Jesus did not preexist as a divine entity but as God's predetermined plan.
Now it is your turn to come up with an honest answer for what Jesus said in John 17:3 (as well as John 5:44) and what Paul wrote in 1 Corinthians 8:6. Also by insisting your interpretation is correct you label Peter a liar since in his Acts 2 sermon he plainly teaches Jesus is a man and God's predetermined plan.