Jesus is referring to the spiritually dead.
In the following verse, those who are in the graves are those who are spiritually dead, in the graves of ignorance.
John 5:28-29 Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
Being born again has nothing to do with the physical body. It is all about the Spirit. To glorify flesh is to deny Jesus.
John 3:5-7 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh; and that which is born of the Spirit is spirit. Marvel not that I said unto thee, Ye must be born again.
Where did Jesus EVER talk about rising from the grave? Jesus said to let the dead bury their dead.
Being born of the spirit has nothing to do with the body. It means spiritual rebirth. Jesus only ever talked about spiritual rebirth, never about the rising of bodies from graves. The Christians just mixed up spiritual with physical.
2 Timothy 1:10 But is now made manifest by the appearing of our Saviour Jesus Christ, who hath abolished death, and hath brought life and immortality to light through the gospel:
This refers to spiritual death being abolished, not physical death. It refers to spiritual life and immortality of the soul that we get through Jesus.
John 5:25-29 Verily, verily, I say unto you, The hour is coming, and now is, when the dead shall hear the voice of the Son of God: and they that hear shall live. For as the Father hath life in himself; so hath he given to the Son to have life in himself; And hath given him authority to execute judgment also, because he is the Son of man. Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
This means that the spiritually dead will hear His voice and they will have eternal life because the Father gave the Son the power to confer eternal life... The hour is coming when those who are spiritually dead (in the graves of ignorance) shall hear his voice.
When the body dies, the soul ascends to the spiritual world and takes on a new form that best befits its station. It gets a spiritual body made up of spiritual elements in the spiritual realm of existence. There is no way we can know what that is like until after we die.
The following verses are referring to a spiritual resurrection, spiritual life, not to physical life.
John 11:23-27 Jesus said to her, “Your brother will rise again.” Martha said to Him, “I know that he will rise again in the resurrection at the last day.” Jesus said to her, “I am the resurrection and the life. He who believes in Me, though he may die, he shall live. And whoever lives and believes in Me shall never die. Do you believe this?” She said to Him, “Yes, Lord, I believe that You are the Christ, the Son of God, who is to come into the world.”