John 3:13 is an interesting verse. I don’t believe Jesus is denying that Enoch or Elijah had been “taken up” to heaven.
That would be against not only the context of the verse but also the context of the conversation.
Enoch, Moses, Abraham and Elijah were not taken up to the third Heaven as some teach as when they were seen (not Enoch or Abraham) of Peter, James and John in Matthew 17:1-9 it was only a transfiguration like a vision that they saw Jesus transfigured as was Moses and Elijah. There is no one in the third heaven except God, Jesus and the angels, John 3:13. Everyone that has ever died is asleep in their grave and when Christ returns they will hear His voice as He calls all of them to come forth, they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation, John 5:28, 29. It is only our spirit/breath/soul that goes back to God who gave it, Genesis 2:7; Ecc 12:7.
Gen 5:24 And Enoch walked with God: and he was not; for God took him.
Hebrews 11:5 By faith Enoch was translated that he should not see death; and was not found, because God had translated him: for before his translation he had this testimony, that he pleased God.
Does not say Enoch was taken up to heaven, but that he was only translated that he should not see death at that particular time being he was 365 years old. Should not see death means since Enoch walked with God he would not see the second death, Rev 20:6, but only that of the first death, Hebrews 9:27, as all his days were three hundred and sixty as he died, but no one knows where.
Genesis 49: 30 In the cave that is in the field of Machpelah, which is before Mamre, in the land of Canaan, which Abraham bought with the field of Ephron the Hittite for a possession of a burying place. 31There they buried Abraham and Sarah his wife; there they buried Isaac and Rebekah his wife; and there I buried Leah.
Deuteronomy 34:5 So Moses the servant of the LORD died there in the land of Moab, according to the word of the LORD. 6 and he buried him in a valley in the land of Moab, over against Beth-peor: but no man knoweth of his sepulcher unto this day.
2 Kings 2:11 And it came to pass, as they still went on, and talked, that, behold, there appeared a chariot of fire, and horses of fire, and parted them both asunder; and Elijah went up by a whirlwind into heaven. (Heaven here means atmosphere, first heaven)
Elijah, having ascended into the air by a whirlwind was carried away out of sight beyond the horizon. Several years after he was taken away King Jehoram received a letter from him. How long after? There are some difficulties in figuring the exact chronology as it varies from 2 to 10 years or more. A note in Josephus (a Jewish historian of the first century A.D.) says 4 years, while the JEWISH ENCYCLOPEDIA figures it at 7 years.
Regardless of the exact number of years there came writing to Jehoram from Elijah the prophet, saying..." (2Chron 21:12). Now the wickedness of Jehoram, for which he was being rebuked in the letter, took place after Elijah was taken away, yet the letter speaks of these things as past events, and the punishment to come upon him as yet future. So the idea of some, that Elijah wrote the letter before he was removed by the whirlwind, is proved wrong.
Elijah was taken up by the whirlwind into the first heaven and transported to another location on Earth. God did not see fit in His purpose to reveal his whereabouts. Chariot of fire is used at times figuratively for host (angels) like in 2 Kings 2:11, 12: 6:17; Psalms 68:17; 104:1-4. Elijah, by his prayers and his counsel was the "chariot of Israel and the horseman thereof", meaning Elijah was the stronghold of Israel, the driving force of God. The Israelites never used chariots till the time of David.
When you compare 2 Kings 2:11-15 with 2 Kings 6:17 you see that God sent the host/angels down to Elijah who caught him up in a whirlwind and translated him to parts unknown. Several years after he was taken away King Jehoram received a letter from him.
Jesus was telling Nicodemus that not only had he come down from heaven, but was in heaven at the same time he was speaking to Nicodemus.
In John 3:1-15 Jesus was still here on earth face to face teaching Nicodemus and as the crucifixion had not happened yet at that time.
Some translations omit the complete verse because they don’t understand it
Some of the newer translations do omit certain things and that is why I only use the KJV and allow the Holy Spirit teach me.
What do you think Jesus meant by saying he came down from heaven and was in heaven while speaking to Nicodemus?
Again, read John 3:1-15 as Jesus had not yet been crucified and still here on earth.