Your observation is incredibly enlightened.
Now we know what the condition was of those who existed before the arrival of Jesus and the preaching of His Gospel. All these people went to the realm of death, to Sheol, the righteous as well as the unrighteous, the believers as well as the unbelievers. The rich man was there, but also Abraham and Lazarus the beggar, although there was a deep gulf between them.
Among the righteous in Sheol, however, there were. also those who during their lives had looked forward to the 'testimony' they had received from God. Abel comes to mind, a man who must have thought about the forgiveness of his sins and reached the conclusion that this could only be brought about by the shedding of blood. Also Abraham, who sought an unseen city, built on the foundation of faith, whose builder and maker is God. The prophets also searched and inquired who these spiritual people might be, which the Spirit in them was speaking of.
All these godly inclined people would reach the final purpose of their faith, that is the salvation of their souls, (lPet 1:9,10), and would be the first to take up their place in the heavenly paradise. These saints were taken out of Sheol at the resurrection of Jesus and replanted in the garden of God.
After their inner men, that is with their spiritual bodies, these saints were in Sheol, the realm of the dead. They were raised, that is, they received a sign that the time had come to rise and start a new period of life. After Jesus' resurrection they left Sheol and went to 'the holy city' which, according to Revelation 2:12, is the New Jerusalem. Here they appeared to many. Being inhabitants of the New Jerusalem these saints manifested themselves on earth in a resurrection body in the same way Jesus did, "And came out of the graves after his resurrection, and went into the holy city, and appeared unto many".
There is yet a second occasion similar to this event spoken of in the Book of Revelation 22:14,15, "Blessed are those who wash their robes, that they may have the right to the tree of life and that they may enter the city by the gates".
Hades, the realm of the dead, contains these two primary groups (among others):
Those of the Old Covenant who were not transferred to the heavenly paradise when Jesus rose from the dead, although they had served God; and those who never had the opportunity to know the true God and never heard the gospel of Jesus Christ, yet did righteousness and sought for good.
John saw how the dead of all ages, except those who shared in the first resurrection and those who were transplanted into the heavenly paradise, now rise from Hades. Then it is fulfilled: "The hour is coming when all who are in the tombs will hear his voice and come forth, those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of judgment", (John 5:28-29). Daniel said this about the second resurrection: "Many of those who sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt", (Dan 12:2). The verse speaks of 'many', not of 'all', for many dead were to share in the first resurrection and never see death. (John 8:51).
Revelation 22:14,15 is speaking about the righteous of all ages who have not reached spiritual maturity as yet.Their robes have been washed and are righteous and they recorded in the Book of Life. For that reason they are entitled to the leaves of the trees of life for healing, that they may be blessed, perfectly saved, and complete. These also share in the glory of the New Jerusalem.