No one has ever entered Heaven, except the one who came from Heaven, the son of man
John3:13
You have a misunderstanding of that verse. It is not teaching that persons like Enoch, Elijah and Moses had not entered Heaven when Jesus made the statement. The entire context is about being born again from Heaven to have the Heavenly mind, as Jesus did:
John 3:13 KJB - And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
All mankind need to be born again, as per verses 3,5,7 KJB. Why? They are all earthly minded, as per John 3:12, for Heavenly persons need not to be born again, but rather those of the earth:
John 3:12 KJB - If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things?
If Nicodemus could not even understand that he needed to be born again, how in the world could Jesus explain to him the things of Heaven, the Heavenly kingdom [see, enter, etc, vs 3,5,7 KJB]. One needs a Heavenly mind to get the spiritual things of Heaven as Jesus explained. The Carnal/Earthly mind is not subject to the Law of God and neither indeed can be, cannot understand spiritual matters of the Heavenly Kingdom:
Romans 8:7 KJB - Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
1 Corinthians 2:13 KJB - Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual.
Therefore, Jesus told Nicodemus, that he needed to be born again to even understand what Jesus was talking about in matters spiritual, and that no man of themselves went from the carnal and looked upward, but always downward on carnal things. It took the Heavenly minded person, to condescend [Philippians 2:5-11 KJB], and to be born on this earth, to bring the Heavenly things to mankind, that they may be born again, and enter into the Heavenly minded things, no longer dwelling upon the fleshly carnal, but that the Holy Spirit would be in control. God, through Christ Jesus and the Holy Ghost, was in effect giving mankind his Kingdom [King's Dominion] back, self-control under/through submission to the higher power, God [as it was in Genesis, for when Adam sinned, he lost self-control, having turned over his submission to another, and thus lost all dominion, including control of himself, for the kingdom of Heaven is within]:
Colossians 3:2 KJB - Set your affection on things above, not on things on the earth.
Context, the Ten Commandments [Exodus 20:1-17 KJB]:
Exodus 20:22 KJB - And the LORD said unto Moses, Thus thou shalt say unto the children of Israel, Ye have seen that I have talked with you from heaven.
1 Corinthians 15:48 KJB - As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
1 Corinthians 15:49 KJB - And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
Philippians 3:19 KJB - Whose end is destruction, whose God is their belly, and whose glory is in their shame, who mind earthly things.)
Philippians 3:20 KJB - For our conversation is in heaven; from whence also we look for the Saviour, the Lord Jesus Christ:
Colossians 3:1 KJB - If ye then be risen with Christ, seek those things which are above, where Christ sitteth on the right hand of God.
Colossians 3:2 KJB - Set your affection on things above, not on things on the earth.
This was where Jesus' always had his
mind/heart [John 3:12 KJB; constantly dwelling upon the Heavenly], on the perfect will [Psalms 40:8; Matthew 6:10; Luke 11:2, 22:42 KJB] of His Father:
John 3:12 KJB - If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things?
John 3:13 KJB - And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.