Question: Lucia was asking about sin and death only being around since Adam. Genesis for Ordinary People highlights Romans 5 and talks about sin being in the world before the law that Adam was given, but what about I Corinthians 15:21-22 which says, 'For since by a man came death, by a man also came the resurrection of the dead. For as in Adam all die, so also in Christ all will be made alive.'?
Answer: There are two Greek words that mean 'man,' - anēr, which refers to a single male individual and anthrōpos, which is the generic term that has the general idea of 'mankind'.
Romans 5:14 informs us that Adam is a symbol, a representation. The NIV calls him "a pattern of the one to come." So it's good to remember that what happened in the garden of Eden is not fiction or a parable, but we can view it as a representation - a microcosm or model of what was happening in the wider world. God used it to show us that since we have fallen we all fall short of the mark he sets.
Adam represents Christ because Christ became a man - "a pattern of the one to come." Adam also represents humanity, hence ‘Adam’ can be singular or plural, i.e. Adam the man or the generic name of the human race. So we can interpret I Corinthians 15:21-22 as the King James Version does by saying, “For since by man came death”, “man” being all humans. We can also view it as one man too, Adam in the garden who disobeyed, but also as all men everywhere at every stage of human history because, since our fall we all miss the mark. (Physical death was there for those before the fall as a teacher of what spiritual death is. Had living creatures not died then God saying, "the day that you eat of it, you will surely die” would make little sense, with no one sure what death was or looked like.)
The word used in Greek for “man” in 1 Cor 15: 21 is “anthropou“; in Galatians 3:15 the same word is translated as “human” – “Just as no one can set aside or add to a human covenant” – So we see how the word "man" can be used to mean a man or man in general. Ecclesiastes 7:29 says, "Behold, I have found only this, that God made men upright, but they have sought out many devices." The first humans endowed with God's image were upright but they went in search of many schemes. Adam, the man, tells our story.