The fact that sin is here today means that something took place to make the world a different place. Death entered the world through that sin. Death is not natural. Just as sin is an aberration, so also death is also an aberration. The nature of sin is the mutilation of life.
Sin brings about death.
It describes a point in time. It looks to the time of Adam s sin. There is a sense in which all people sinned when Adam sinned because he was the federal head of the human race. All are corrupt - everyone has inherited a sin nature from Adam. All mankind was mystically and genetically in Adam and so all sinned.