Q. Okay, here's the thing I'm wondering about...
Jesus said "no one has ascended into heaven, but He who descended from heaven, even the Son of Man". But then there's Enoch and Elijah who, I guess, were taken to heaven, even 2 Kings 2:11 says Elijah was taken in a whirlwind to Heaven.
A. Jesus is essentially saying to Nicodemus that He has the words of eternal life, and is connecting himself to God's way ---stated in Deut. 30---- of freely distributing His words of life to man.
"For this commandment which I command you today is not too difficult for you, nor is it out of reach. It is not in heaven, that you should say, 'Who will go up to heaven for us to get it for us and make us hear it, that we may observe it? Nor is it beyond the sea, that you should say, 'Who will cross the sea for us to get it for us and make us hear it, that we may observe it? But the word is very near you, in your mouth and in your heart, that you may observe it" Deut 30:11-14Those who now have received the words of life that have come down from heaven are on the "distribution team"---like Paul---and all of us.
But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down [from above] Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.) But what saith it? The word is nigh thee, [even] in thy mouth, and in thy heart: that is, the word of faith, which we preach; Rom 10:6-8In other words, we don't have to be like Indiana Jones, "In Search of the Words of Life"...God sends them down from heaven and they are distributed freely by his people.
To have doubts about John 3:13 because Enoch and Elijah were received up to heaven misses the point of the imagery----i.e. Enoch and Elijah weren't climbing up to heaven in order to seek and obtain God's words of life.