All humans were appointed to die once and then the judgement. Under law, all humans died to the law. Only one human could live under old covenant law and even He was appointed to die once. He died to make a new covenant for His Jewish people. The Holy Spirit resurrected Him because the first death could not hold Him. He was judged worthy to be resurrected rather than die a second death in the lake of fire along with Hades. The two possibilities for a human in his first death were: resurrection with Christ or second death, which was destruction.

Hebrews was written to old covenant Hebrews who were previously only cleansing their flesh with animal sacrifices, until the time of their reformation came. Then they cleansed their conscience from their dead works under law, through the eternal spirit of Christ, who entered the real Holy place in heaven to appear for them. The new covenant was specifically created to save those in the old covenant; “for redemption of transgressions under the first covenant”. Gentiles were adopted into the living body of the saved Hebrews. Their is only one body of Christ.

Hebrews 9:10-15

YLT ¹⁰ only in victuals, and drinks, and different baptisms, and fleshly ordinances—till the time of reformation imposed upon them . ¹¹ And Christ being come, chief priest of the coming good things, through the greater and more perfect tabernacle not made with hands—that is, not of this creation— ¹² neither through blood of goats and calves, but through his own blood, did enter in once into the holy places, age-during redemption having obtained; ¹³ for if the blood of bulls, and goats, and ashes of an heifer, sprinkling those defiled, doth sanctify to the purifying of the flesh, ¹⁴ how much more shall the blood of the Christ (who through the age-during Spirit did offer himself unblemished to God) purify your conscience from dead works to serve the living God? 
¹⁵ And because of this, of a new covenant he is mediator, that, death having come, for redemption of the transgressions under the first covenant, those called may receive the promise of the age-during inheritance,

Hebrews 9:27-28

ECB ²⁷ And as it is laid out for humanity to die once and after this the judgment: ²⁸ thus the Messiah was offered once to offer the sins of many; and to them who await him he appears the second – apart from sin to salvation.

Hebrews chapter 9 is about typical old covenant high priests who entered behind the second veil once a year with the blood of animals for the sins of Israel. They offered blood for themselves too because they were not apart from sin. Then came the final sacrifice of the one human who was apart from sin. He went into the second veil in the true tabernacle in heaven. The one in Jerusalem was only a copy of the one in heaven. ECB is the only translation of Hebrews 9:28 that I could find that did not add the word “time” to the text after the word “second”. Yet they failed to translate the Greek word “ek”,, which clearly means “out” in English.

Hebrews 9:27-28 – And according as it is appointed to the humans to be dying once and after this comes judging. so Christ was once offered to be bearing the sins of many. Out of second apart from sin He shall appear to the ones awaiting – into salvation.

If the sacrifice of the eternal high priest being accepted in the true tabernacle in heaven isn’t unto salvation for the old covenant believers who were previously dead under law, then what will be? When the new covenant high priest is seen coming out of the second veil alive, that is salvation to Israel. The sacrifices ceased to be offered after Christ came out of the most Holy Place of the true tabernacle in heaven, because He was without sin. Every other priest had to offer sacrifice for himself too.

Hebrews 9:7-8

YLT ⁷ and into the second, once in the year, only the chief priest, not apart from blood, which he doth offer for himself and the errors of the people, 
⁸ the Holy Spirit this evidencing that not yet hath been manifested the way of the holy places, the first tabernacle having yet a standing;

Hebrews 10:1-2

YLT ¹ For the law having a shadow of the coming good things—not the very image of the matters, every year, by the same sacrifices that they offer continually, is never able to make perfect those coming near, ² since, would they not have ceased to be offered, because of those serving having no more conscience of sins, having once been purified?

Jesus became a Hebrew who was also appointed to die once and then came the judgement.

Hebrews 10:9-10

YLT ⁹ then he said, `Lo, I come to do, O God, Thy will;’ he doth take away the first that the second he may establish; ¹⁰ in the which will we are having been sanctified through the offering of the body of Jesus Christ once,

Hebrews 10:15-17

YLT ¹⁵ and testify to us also doth the Holy Spirit, for after that He hath said before, ¹⁶ `This is the covenant that I will make with them after those days, saith the Lord, giving My laws on their hearts, and upon their minds I will write them,’ <sup>17</sup> and `their sins and their lawlessness I will remember no more;’

His flesh was the most holy place on earth. Then He sent the Holy Spirit to make His people the most Holy Place on earth.

Hebrews 10:20

YLT ²⁰ which way he did initiate for us—new and living, through the vail, that is, his flesh—

Hebrews 9:24

YLT ²⁴ for not into holy places made with hands did the Christ enter—figures of the true—but into the heaven itself, now to be manifested in the presence of God for us;

“for us” is for the Hebrews. The Gentiles were adopted into the resurrected Hebrew body.

Hebrews 10:38-39

YLT ³⁸ and `the righteous by faith shall live,’ and `if he may draw back, My soul hath no pleasure in him,’ ³⁹ and we are not of those drawing back to destruction, but of those believing to a preserving of soul. 

The Hebrews judged to be righteous in Christ were the believers that accepted God’s grace. They received their eternal inheritance in heaven. The unbelievers drew back into the old covenant and faced destruction, which was their second death as an old covenant nation.

Hebrews 10:27-30

LITV ²⁷ but a certain fearful expectation of judgment and “zealous fire being about to consume the adversaries.” Isa. 26:11 ²⁸ If anyone did not regard the Law of Moses, that one dies without pities on ” the word of two or three witnesses.” Deut. 17:6 ²⁹ How much worse punishment do you think will be thought worthy to receive, the one trampling the Son of God, and having counted common the blood of the covenant in which he was sanctified, and having insulted the Spirit of grace? ³⁰ For we know Him who has said, “Vengeance belongs to Me; I will repay,” says the Lord. And again, “The Lord will judge His people.” Deut. 32:35, 36

1 Peter 4:17

LITV ¹⁷ Because the time has come to begin the judgment from the house of God; and if firstly from us, what will be the end of the ones disobeying the gospel of God?

Peter, who also wrote to the Hebrews in diaspora, confirms that the judgement to resurrection preceded the judgement to the second death of the nation in the flesh. The believing Hebrews were not with the unbelieving Hebrews who were about to be judged to destruction. Loosing one’s salvation was real for the Hebrew people of God during their covenant transition.

Hebrews 10:37-39

LITV ³⁷ For, yet a very little and the One coming will come, “and will not delay.” Hab. 2:3 ³⁸ “But the just shall live by faith;” “and if he draws back,” “My soul is not pleased in him.” Hab. 2:4 ³⁹ But we are not of those withdrawing to destruction, but of faith, to the preservation of the soul.