If you don't understand about original sin, I don't think you've understood anything about God, the Bible, or human history even. Adam was created perfect, and Eve out of Adam. Eve was deceived by Satan into thinking that they could be like God. (Satan is still using this deception today, in pretty much every man-made religion, that is, everything but Christ.) Adam and Eve disobeyed God, their Creator, being warned previously that such disobedience would cause them to die. Die they did, and the human race was cursed with death and all of creation cursed with them.