Note that there is nothing stating that nephesh, the part of existence man has it common with all living creatures, is immortal or lives forever. In fact, the Bible is clear that this physical part of man CAN and DOES die. It is mortal and not conscious after death.
Behold, all souls (in this context it means those who have life) are Mine . . . The soul that sins, it shall die (Ezekiel 18:4)
the living know that they shall die; but the dead do not know anything, nor do they have any more a reward; for their memory is forgotten (Ecclesiastes 9:5, see also 3:19)
God gave humans the ability to live a physical life and to think, create and chose. The Bible calls the entity that makes this possible in every human the "spirit in man." This non-physical component enables humans to be conscious, to be able to think, choose and feel, and have a relationship with God.
But there is a spirit in man . . . (Job 32:8)
Thus says the LORD, who stretches forth the heavens . . . and forms the spirit of man within him (Zechariah 12:1)
Human life is unique in all of creation. It is the ONLY thing that possesses both physical and spiritual existence.
Man's spirit upon death
When our life ends in death the physical part of our existence, our bodies, returns to the ground from where God made it (Genesis 3:19). However, what happens to the spirit in man? Where does it go when we die? Wise King Solomon also wondered what happens to this spiritual component of humans.
21 How can anyone be sure that the human spirit goes upward while an animal’s spirit goes down into the ground? (Ecclesiastes 3:21)
Solomon answers his own question in the above verse a few chapters later.
7 Our bodies will return to the dust of the earth, and the breath of life (our human spirit) will go back to God, who gave it to us (Ecclesiastes 12:7)
At death, the spirit of man returns to God who gave it. King David also understood that God was the owner of this spirit.
Into Your hand I commit my spirit; (Psalm 31:5, see also Luke 23:46)
Revelation also tells us that man's spirit (in this case, of those who are true Christians) belongs to God (see Revelation 6:9-10).
Do the dead merely SLEEP?
Several verses in the Bible talk of those who are dead as being in a state of dreamless sleep. This is because those who have died are not conscious nor have any thoughts (Psalm 146:4; Ecclesiastes 9:5-6).
And many of those who sleep in the dust of the earth shall awake . . . (Daniel 12:2)
He (Jesus Christ) said to them (his disciples), 'Our friend Lazarus has fallen asleep . . .' (John 11:11, see also 1Corinthians 11:30, 15:51-52)
The countless humans who have ever lived and are now dead are unaware of the passing of time. The time period from their death to when God resurrects them will seem, to them, like one occurred immediately after the other - even though the actual time between the events may be thousands of years apart.
More than one resurrection
The Bible delineates not just one, but two (and likely three) resurrections back to life. The purpose of the first one is to give God's elect, at the return of Christ to the earth, immortality.
There will be the shout of command, the archangel’s voice, the sound of God’s trumpet, and the Lord himself will come down from heaven. Those who have died believing in Christ will rise to life first; (1Thessalonians 4:16, see also Matthew 24:29-31 and 1Corinthians 15:51-52)
The SECOND "life after death" resurrection from the dead occurs after what is called the Millennium, or Jesus' reign on earth for a thousand years.
"(But the rest of the dead did not live again until the thousand years were completed.) This is the first resurrection" (Revelation 20:5).
The purpose of this, the greatest resurrection, is to offer those who never had a FULL opportunity for salvation a chance to live God's way and accept his gift of immortality. The vast number of humans who have ever lived will populate this resurrection. These either never heard the gospel message, heard only part or received a counterfeit message, or may have heard it but God decided at the time not to open their minds and hearts to his truth.
Though not conclusive, Isaiah 65 seems to show that God will grant a one hundred year life span to human beings in the second resurrection (Isaiah 65:20). God will judge those who are resurrected back to a physical existence in the same way He NOW judges those who are true Christians - by His words in the Bible. These countless billions of unsaved people will have a FULL chance to understand the Gospel and live forever.
There is also some evidence that God will have a THIRD resurrection, a resurrection to life whose purpose is to deal with the incorrigibly wicked by executing them forever - a final death from which there will be no resurrection.
Life after death does exist!