John 3:13 is present tense, as in "Not one CAN ascend into Heaven...." I believe it's clear that Enoch didn't die. neither did Elijah. I also believe they will return and die as the two witnesses, a literal fulfillment of the prophecy in Revelation. Remember also Mat. 17, in which Moses and Elijah appeared with Yashua ( although Moses died, he was seen talking with Yahshua). But Enoch and Elijah are the only 2 people who never died.
Also I'm not sure what you mean by "Yeshua was the first-born therefore no one entered heaven before Him". Yahshua was already in Heaven before He came to Earth as a mortal. He only returned to Heaven. Since Moses and Elijah were with Yahshua on the mount, where are they now? Did Yahshua just raise them up for a 5 minute chat, and then put them back to sleep? I doubt that very much.
John notes in 3:13: "AND no man hath ascended into heaven, but he who descended from heaven, the Son of man, he who is in heaven".
ויתהלךH1980 we ith halek חנוךH2585 Chaok אתH854 tha האלהיםH430 ha Elohim: ואיננוH369 we ain’nu; כיH3588 chi לקחH3947 leqch אתו athu H853 אלהים׃H430 Elohim
And walked Hanoḵ with Elohim and then was not our, for took him Elohim.
Enoch with his own power was not "ascended into heaven" "for took him Elohim".
Enoch ascended into heaven in a whirlwind, with horses and chariots of fire (acording to Iasher 3:36), in same way as the two "went on and talked, behold, there appeared a chariot of fire and horses of fire, and separated the two; and Elijah went up by a whirlwind into heaven".
No man hath ascended into heaven, but He who descended from heaven, while He has spoken: "while they beheld him, he was taken up, and the cloud received him, and he was covered from their eyes.
And while they looked into heavens as he went, two men were found standing with them in white vestments; and they said to them:
Men, Galiloyee! Why stand you looking into heavens this Yeshua who is taken up from you into heavens will so come as you have seen him ascend into the heavens". (According to Acts of Apostles 1st chapter)
Apocalypse 11:11-12: "And after those three days and a half, the spirit of life from Elohe entered into them, and they arose upon their feet. And great fear fell upon them who saw them. And they heard [POLYGLOTS] a great voice from heaven, saying to them: Ascend hither! And they ascended to heaven in a cloud, and their adversaries beheld them".
Messiah was once offered to abolish sin (according Hebrews 9:26-28), "but/and as it awaits men to die once, and/but after this the judgment": (Verse 28)
"so also the Messiah, having been offered once to bear the sins of many, shall appear a second time, apart from sin, to those waiting for Him, unto deliverance".
Regarding the promise: "AMEN, I say unto you, there are men [HM: l’kem H559 şe’iş H3117-3427 me H4100 a’mdim H5975 phe H6311 : first steadfast …] standing here who shall not taste death, until they shall have seen the Son of Man [HM: H935 (Boe) (like in: Gen 7:13; 16:13 ) H4438 (b’malkut’u) : entered …] coming in his Kingdom". – Mathew 16:28;
This was fulfilled here: And he said, Behold, I see the heavens opened, and the Son of Man standing at the right hand of Elohe. – Acts of Apostles 7:56;
Some say all men from goyim will die, but the Prophet says al nations will ascend to Jerusalem for warfare.
Regarding the promise:
Some say all people from Israel will taste dead at least once when Messiah, the Son of Man, "shall appear a second time" (according Hebrews 9:26-28) but Paul writes about "those waiting for Him, unto deliverance" and the Prophet says: "but half of the people shall not perish from the city" and "the inhabitants of Jerusalem […] shall mourn for Him".
"BEHOLD, the day of the LORD is coming, and your spoil shall be divided in the midst of you.
For I will gather all nations against Jerusalem to battle; and the city shall be taken and the houses plundered and the women ravished; and half of the city shall go into captivity, but half of the people shall not perish from the city. Then the LORD shall go forth and fight against those nations as when he fought in the day of battle.
And his feet shall stand upon the Mount of Olives [...]" - Zechariah 14:1-4a;
And I will pour upon the House of David, and upon the inhabitants of Jerusalem, the spirit of favour and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for Him, as One mourneth for His only Son, and she will be in bitterness for him, as One that is in bitterness for His firstborn. - Zechariah 12:10.
And it shall come to pass, that - every one that is left of all the nations - which came against Jerusalem shall even go up from year to year to worship the King [translated I other versed: Angel of] Yahweh Tzebaot, and to keep the Feast of Tabernacles. - Zechariah 14:16.