● Gen 2:15-17 . .The Lord God took the man and put him in the Garden of Eden to work it and take care of it. And the Lord God commanded the man, "You are free to eat from any tree in the garden; but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die."
I'm confident in my own mind that death was common in Adam's garden due to the natural life cycles of bugs, birds, beasts, and vegetation. So he fully understood the threat. But apparently the prospect of his own death gave Adam no cause for alarm; he ate from the tree in spite of God's warning.
● Gen 3:6 . .When the woman saw that the fruit of the tree was good for food and pleasing to the eye, and also desirable for gaining wisdom, she took some and ate it. She also gave some to her husband, who was with her, and he ate it.
Now, prior to tasting the forbidden fruit, Adam and his wife were comfortable in the buff.
● Gen 2:25 . .The man and his wife were both indecently exposed, and they felt no shame.
A very definite transformation occurred in Adam when he ate the fruit; easily seen by the fact that he suddenly became no longer comfortable in the buff like before.
● Gen 3:7 . .Then the eyes of both of them were opened, and they became aware that they were indecently exposed; and they sewed fig leaves together and made themselves loin coverings.
Not only did Adam become uncomfortable in the buff, but for the very first time on record he experienced fear.
● Gen 3:8-10 . .Then the man and his wife heard the sound of the Lord God as he was walking in the garden in the cool of the day, and they hid from the Lord God among the trees of the garden. But the Lord God called to the man, "Where are you?" He answered, "I heard you in the garden, and I was afraid because I was indecently exposed; so I hid."
In other words: in spite of his little apron, Adam still felt indecently exposed; and not only that; but he also felt vulnerable; defined by Webster's as capable of being physically or emotionally wounded and/or open to attack or damage.
Where before; prior to eating the forbidden fruit, Adam was indifferent to death; all of a sudden it loomed large in his thinking because of his newly-acquired sense of vulnerability.
Thanatophobia is psychological jargon for fear of death. Everybody has it to one degree or another. Most of us merely dread death; i.e. we're aware it's inevitable but we don't let it get to us except maybe in times of mortal danger; while others suffer all the time with a stubborn, deep-seated anxiety about dying.
According to the Bible; fear of death associates humanity with the Devil.
● Heb 2:13-16 . . "Here am I, and the children God has given me." Since the children have flesh and blood, he too shared in their humanity so that by his death he might destroy him who holds the power of death-- that is, the Devil --and release those who all their lives were held in slavery by their fear of death.
Christians aren't freed from the fear of death via their trust in Christ's crucifixion. No, they go right on dreading it as usual. I'm 74 years old and have been among Christians all my life; both in church and out of church. In all my years I've yet to meet even one Christian who no longer dreads death; they all continue to dread it and I'd really have to question both their sanity and their honesty if they didn't. (I would also question their self-awareness; for example Peter thought he was unafraid of death, but turned out he really was.)
Due to Christ's crucifixion, the fear of death no longer associates the children of God with the Devil; viz: though their fear of death isn't gone, the association is gone. In my mind's eye that is really important because people associated with the Devil are on track to share his fate.