You missed one of the questions. What was the result of sin?
The fall. When man was a mere beast, with no ability to choose good or evil, he had no sin. After Adam was ensouled, he became capable of sin, but had free will with regard to it. Having never before sinned, he was innocent. Adam chose sin by disobeying God, lost his innocence, and that sin nature was inherited by all his offspring, thus necessitating a savior for the redemption of Adam's offspring (Man cannot live in eternity with God unless in a state of grace, thus the need for redemption). Of course God knew Adam would choose sin, but that doesn't negate the fact that he had free will in sin's regard. He was free to choose to remain innocent, but didn't. We, being Adam's offspring, share this tendency towards sin.
