That's correct. Nowhere did Paul show that our flesh body is translated to the 'spiritual body'. Only in the following verses did Apostle Paul hint about Lord Jesus' flesh body being made "a quickening spirit"...
1 Cor 15:45-47
45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
47 The first man is of the earth, earthy: the second man is the Lord from heaven.
KJV
He says nothing about his "flesh body" being made into a spirit - that's just your assumption. John 1:14 (KJV) says:
(14) And the Word was
made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
(or more precisely translated, "The Word became flesh"). He was totally human. His spirit body didn't become flesh, God gave him a human body, prepared in Mary's womb. As Paul said, Hebrews 2:14 (KJV):
(14) Forasmuch then as the children are partakers of flesh and blood,
he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil;
He was no longer a spirit being while he was human, and he is no longer a human being now that he has been made a spirit being. As Paul said, first he had a human (natural) body, but then afterwards he was given a spirit body - they are completely different; you can't have two bodies at the same time (although spirit beings can temporarily produce a human body and use it to interact with humans). Consider the whole passage, not just one verse in isolation - 1 Corinthians 15:36-49 (WEB):
(36) You foolish one, that which you yourself sow
is not made alive unless it dies.
(37) That which you sow,
you don’t sow the body that will be, but a bare grain, maybe of wheat, or of some other kind.
(38) But
God gives it a body even as it pleased him, and to each seed a body of its own.
(39) All flesh is not the same flesh, but there is one flesh of men, another flesh of animals, another of fish, and another of birds.
(40) There are also celestial bodies, and terrestrial bodies; but the glory of the celestial differs from that of the terrestrial.
(41) There is one glory of the sun, another glory of the moon, and another glory of the stars; for one star differs from another star in glory.
(42) So also is the resurrection of the dead. The body is sown perishable; it is raised imperishable.
(43) It is sown in dishonor; it is raised in glory. It is sown in weakness; it is raised in power.
(44)
It is sown a natural body; it is raised a spiritual body.
There is a natural body and there is also a spiritual body.
(45) So also it is written, “The first man, Adam, became a living soul.” The last Adam became a life-giving spirit.
(46) However that which is spiritual isn’t first, but
that which is natural, then that which is spiritual.
(47) The first man is of the earth, made of dust. The second man is the Lord from heaven.
(48)
As is the one made of dust, such are those who are also made of dust; and as is the heavenly, such are they also that are heavenly.
(49) As
we have borne the image of those made of dust, let’s also bear the image of the heavenly.
And with 1 Corinthians 15:50, Paul made it plain that a flesh body of corruption cannot inherit the kingdom of Heaven. That is what Paul was showing us with that, "the last Adam was made a quickening spirit" about Lord Jesus. His flesh body was never found. But that event about Lord Jesus involved His resurrection only. Paul made it clear in that same chapter (and in 2 Corinthians 5), that for us, we must cast off our flesh body in order for our "spiritual body" to manifest.
We don't cast off our human body! We don't have a spirit body living inside our human body. We die, and our dead bodies decompose over time back to dust (maybe quickly if we are cremated and our ashes scattered to the wind or on water!). At a future date God will resurrect us to life and give us new bodies. Christians are resurrected first and given spirit bodies, the rest of mankind are resurrected later and given new human bodies. Jesus, of course, as the head of the Church, was given a spirit body - having the same immortal divine nature as God.
So how does all that above fit with what Apostle Paul taught about the "spiritual body" in 2 Corinthians 5 and 1 Corinthians 15, and... this transfiguration of Christ seen talking with Moses and Elijah?
Again, being given a spiritual body when resurrected only applies to Chistians; it does not apply to Moses and Elijah. (In the vision they were seen as ordinary men.)
That brings us back to the 1 Peter 3 Scripture too...
1 Peter 3:18-20
18 For Christ also hath once suffered for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh, but quickened by the Spirit:
<snip>
So what part was 'quickened by the Spirit'?? Are you going to try and tell me that Lord Jesus of Nazareth, Immanuel 'God with us', needed His Spirit to be quickened at His resurrection? If God needs quickening of His Spirit then He is not God. But Lord Jesus is GOD The Son, even in the flesh, which is what His name 'Immanuel' in Isaiah 7 means (see Matthew 1:23 also).
Quickened means being given life, or restoring to life. More modern translations say (e.g. WEB, MKJV), "being put to death
in the flesh, but made alive
in the spirit". It's saying that he was a human (flesh) when he was killed, but he was restored to life as a spirit being.
Jesus is not God, nor "God The Son". God doesn't need his spirit to be given life, for He is immortal and has never died. Jesus has died (Revelation 1:18) and therefore he needed God to give him life again. If you believe in the Trinity error then I'm not surprised that you try and force other Scriptures to harmonise with it, and end up with further misunderstandings.
It appears that you have much Bible study to do on this matter, as there are many Bible Scriptures you have not gotten to, and not even aware of. I know this for a fact just by your doctrine that you haven't studied this matter thoroughly, but are just regurgitating of lot of men's traditions that you have latched onto instead, ideas that I have heard from others many times before you.

That's very presumptuous!