Artful, and Lv4fer,
I apologize for the delay in posting the different lines of thought about Jesus being the first to ascend to Heaven. I was hoping to be able to post this information sooner.
Line of Thought # 1: Jesus Christ was the first Person to go to Heaven, ever:
Some Christians believe that Jesus Christ is the first Person ever to go to Heaven, based on the following Scriptures:
John 3:13: No one has ascended into Heaven, except He who descended out of Heaven, the Son of Man, who is in Heaven.
Acts 2:34: For David did not ascend into the Heavens...
1st Corinthians 15:20: But now Christ has been raised from the dead. He became the First Fruits of those who are asleep.
Revelation 1:5: and from Jesus Christ, the Faithful Witness, the Firstborn of the dead, and the Ruler of the kings of the Earth. To Him who loves us, and washed us from our sins by His Blood;
And, most of the Christians who believe this line of thought, also believe that everyone who died before Jesus Christ was resurrected, their souls/spirits went to the Paradise in Hades/Sheol [the land of the dead, where souls go to], which is also known as "The Bosom of Abraham". And, most of these Christians also believe that there are two separate parts of Hades/Sheol: One is a Paradise where the servants of God went when they died, and the other is a place of fiery torment, where everyone else went when they died.
This line of thought might explain why Jesus said that Lazarus went to "Abraham's bosom" instead of saying Lazarus went to "Heaven", and it might also explain why Jesus told the thief on the Cross that he would go to Paradise, instead of saying he would go to Heaven.
And I believe that most of the Christians who believe this line of thought, believe that Jesus, as a Soul/Spirit, separate from His Body, went to the Paradise of Hades/Sheol when He died, and then on the third day, Jesus rose out from Hades, took His (now-glorified and immortal) Human Body back, and also, when Jesus ascended into Heaven, He took all of the servants of God who were resting in the Paradise of Hades, to Heaven to be with Him forever.
Matthew 27:52-53: The tombs were opened, and many bodies of the holy ones who had fallen asleep were raised; and coming out of the tombs after His [Jesus'] resurrection, they entered into the Holy City and appeared to many.
These Christians also believe that now, whenever anyone who believes in Jesus Christ dies, they go directly to Heaven as a soul/spirit to be with Jesus, and then, at the Rapture, they will receive Immortal Glorified Bodies.
Also, when God "took" Enoch, He took his soul/spirit to the Paradise of Hades/Sheol.
This line of thought makes a lot of sense to me, and I believe it is in harmony with most, if not all, of the Bible.
However, a couple of Scriptures that might be hard to explain using this line of thought are 2nd Kings 2:1 and 2:11:
2nd Kings 2:1: It happened, when Yahweh would take up Elijah by a whirlwind into Heaven, that Elijah went with Elisha from Gilgal.
2nd Kings 2:11: It happened, as they still went on, and talked, that behold, there appeared a chariot of fire, and horses of fire, which parted them both apart; and Elijah went up by a whirlwind into Heaven.
Perhaps, this "Heaven" was the Paradise of Hades/Sheol. Or, perhaps the 2nd Line of Thought is correct?
Line of Thought # 2: Jesus Christ was the first Person to go to Heaven with a glorified immortal body:
Some Christians believe that when the Bible says that no one ascended to Heaven before Jesus Christ, it means that no one ever ascended to Heaven with a glorified immortal body.
The Bible says that Jesus is the "Firstborn of the dead" and the "First Fruits of the dead", however, we know that other people were raised up from the dead before Jesus was (in fact Jesus resurrected at least 3 people while on Earth), however, all of those people were raised up in corruptable sinful human bodies, and their resurrections were temporary and the people died again later, so, when the Bible says that Jesus was the "Firstborn of the dead", it must mean that Jesus was the First Person ever to be raised up Immortal with a Glorified Body.
These Christians believe that, in the same way that Jesus was the First Person to be resurrected in an Immortal Body, that when the Bible says that Jesus is the First Person to ascend to Heaven, it means that He was the First Person to ascend to Heaven with an Immortal Body.
These Christians believe that all faithful servants of God who have ever died [before and after the resurrection of Jesus], have gone directly to Heaven as souls/spirits to be with God.
These Christians also believe that at the Rapture, all human souls in Heaven will receive Immortal Glorified Bodies [and this is called "The Resurrection"].
To be honest with everyone, I am not really sure which line of thought is correct. I definitely am going to do more studying on this subject.