New Defender's Study Bible Notes
15:21 by man came death. There was, therefore, no death before man. See Romans 5:12. This one verse (as well as the coherent teaching of all Scripture) disproves the false teaching that there were long ages before man, as supposedly identified by the fossil remains of organisms living in those ages. The fossil record, containing the remains of billions of now-dead animals and man-like creatures, cannot be the record of long ages of evolution. It is rather the record of one age of cataclysmic death, at the time of the great Flood, when “the world that then was, being overflowed with water, perished” (II Peter 3:6) and “all that was in the dry land, died” (Genesis 7:22). Not only is this the explicit teaching of Scripture, it is also implicitly taught by the fact that nowhere in the Bible is there the slightest hint of the death of sentient life, either human or animal, before Adam’s sin brought God’s curse of decay and death on man’s dominion, “the whole creation” (Romans 8:20-22). It is further supported by geological evidence everywhere in the crust of the earth.
15:22 in Adam all die. Adam was certainly a real individual man, just as real as Jesus Christ. Since he was the first man, all of us were implicitly “in Adam,” and therefore we have all (except Christ) inherited his sin-nature.