Adam and Eve did not obey God, so they died. Genesis 3:6, 23
Eve listened to the serpent and ate of the fruit. Afterward, she gave some to Adam, and he ate it.
What they did was wrong
Life was hard for them and their children. They grew old and died. They did not go to the spirit world; they ceased to exist.
The dead are as lifeless as the dust. Genesis 3:19
We die because we all come from Adam and Eve. The dead are not able to see or hear or do anything.
Jehovah did not mean for people to die. Soon he will bring back to life those asleep in death. If they listen to him, they will live forever.