Final answer:
The question pertains to the biblical narrative in Genesis where through man, specifically Adam, came the creation of woman (Eve) and the introduction of sin when they ate the forbidden fruit, altering human history and existence.
Step-by-step explanation:
The question '15:21 By man came what two things?' seems to be referencing a biblical context, specifically the biblical account of creation and the fall of man in the book of Genesis. If we examine the scriptures and philosophical interpretations, we can understand that through man, specifically Adam as the first man according to the Genesis narrative, came both the creation of woman and the introduction of original sin to humanity. This can be seen in the scriptures where God created a woman (Eve) from Adam's rib, establishing the human relationship of marriage and companionship (Genesis 2:21-22) and later when Adam and Eve eat the forbidden fruit, leading to the fall and the understanding of good and evil, thus introducing sin into the world (Genesis 3:6-7).
Additionally, these two key events that came 'by man' have profound theological and philosophical implications, encompassing themes of human existence, purpose, and morality, as exemplified by their pivotal role in the salvation narrative of humankind within Christian theology.