Every human is made in the image and likeness of God, having intellect, feelings, and free will. We are morally responsible for our actions and their consequences. In addition, since humans are communal, the actions of the individual affect the broader community.
Adam and Eve chose to sin, and their free will decision affected the whole of humanity. All human descendants from Adam are born with a sin nature and are separated from fellowship with God. We are spiritually dead, incapable of earning salvation from sin.