The reason for universal death is universal sin.
By birth I was born spiritually dead. I had a body and soul but the spirit was like a corpse carried in my flesh with no ability to receive the things of God. It could only receive the things of the world, the flesh and the devil.
When I was told the news that God sent His Son to die in my place for the forgiving of my sins, I believed.
“And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up; that whosoever believeth may in him have eternal life.”
**John *3:14-15 *ASV
http://bible.com/12/jhn.3.14-15.asv
Eternal life is the spiritual life of the soul. Adam was created a "living soul" and he was alive to God because his spirit had not been effected by sin. It is the same life of the spirit that will be eternal for the redeemed.
My spirit is now alive by grace and by the Spirit of God dwelling in me.
The value of man is his spirit but that spirit must go thru regeneration, the new birth. Once a human being is regenerated that individual is truly valuable and their value is manifested in the fruits of the new born human spirit of Galatians 5.