God made man in his own image, but did not make him immortal or of the same substance that he possesses. Our Creator is composed of spirit and is eternal. Humans were made, however, out of the ground or organic substance that constitutes the earth. Adam only became a "living being" (but not an immortal soul) when God breathed life into him (Genesis 2:7).
The first lie, in the Garden of Eden, the devil wanted Eve to believe revolves around the concept of an immortal soul! Eve stated she was instructed not to eat from the tree of the knowledge of good and evil or else she would die (Genesis 3:2 - 3). Satan countered that God was lying and that she would not perish (verse 4)! If humans possessed an immortal part of their existence that lives on after death (they always have a conscious existence), then one has to admit the devil was correct!
If the devil's immortal soul teaching that humans never fully cease to exist upon death was the truth, then God's judgment of Eve would not be righteous! If humans, however, were not endowed with something that was immortal and conscious after death, then the devil LIED to Eve. Her belief, therefore, in his lies constituted a sin and brought upon herself (and Adam) God's righteous judgment.
Here is something else to consider. God's justification for casting Adam and Eve out of the Garden was, "lest he (Adam and Eve) put out his hand and take also of the tree of life, and eat, and live FOREVER" (Genesis 3:22). If all humans automatically have a soul that continues their life forever after death then God's concern makes no sense! His barring them from the Tree of Life would not make a difference since they would already possess something that would keep them alive into the future!
If, however, Adam and Eve did not possess an immortal soul that allowed them to live forever, then God's concern about them acquiring this ability is justified. He did not want his greatest creation, in a rebellious state of mind, to exist forever in unhappiness and misery. The Bible unquestionably states that the ability to live forever is a gift from God to those who obey him (1Corinthians 15:50 - 55, 2Timothy 1:9 - 10, Romans 6:23, etc.).
Is it in the Bible?
Interestingly, the word "immortal" (with no "soul" attached to it) is not found in the Old Testament, either in our English translations or in the original Hebrew text. It is used, however, once in the New Testament. The word immortal in 1Timothy 1:17 is used to refer to one of God's (not man's) attributes.
The original Greek word from which we get our English word "immortal" is aphthartos (Strong's Concordance #G862). It occurs only six other times (Romans 1:23, 1Corinthians 9:25, 15:52, 1Peter 1:4, 23, 3:4) and is usually translated as 'incorruptible,' meaning something that can never decay or perish, or something that endures.
The attribute of being immortal is never applied in the Bible to anything the average human possesses on planet earth. This is diametrically opposite to the teaching that every human has a soul that continues to live after their physical death.
It was after God brought forth man out of the dirt and gave him life that he became a "living soul" or a 'living being.' The Hebrew nephesh (Strong's #H5315) is the word translated as 'soul' and 'being' in most Bibles. It is used to refer to fish (Genesis 1:20), birds (verse 22), cattle and other animals (verse 24) and of course man (Genesis 2:7).
Human life itself, and not some added immortal spiritual piece, is referred to in the Bible as a soul! Psuche (Strong's #G5590) is a Greek word that is virtually equivalent to the word nephesh in the Hebrew. It is the only New Testament word translated as "soul." It generally means any living, breathing creature that is inherently not immortal.
The Bible defines Man as a living being, life, and so on that is mortal. Man has never had an immortal soul that allows any part of him to live past death. The only means by which a person can live into eternity is to repent of their sins, receive God's spirit, live a life of obedience and then receive it as a gift.