In the begining, God created the universe perfect. He also gives all of his creation free will. When God created the angels in heaven, Lucifer became proud and rebeled. Lucifer wanted to take over the throne of God, he wanted to rule in God's place and have all the power, to dominate the universe. Some theoligians say Lucifer became jealous when God began tocreate humanity, when He started to create Adam. Some think Lucifer feared God would love the new human race more than he loved the angelic race, that he would love Adam more than Lucifer.
Lucifer rebeled against god and took one third of the angels with him when he fell from heaven. He became Satan, the Adversary.
Then, God put Adam in the garden of Eden, and later created his wife Eve from his rib. In the garden of Eden everything was perfect. But there was the tree of knowledge of good and evil, whose fruit Adam and Eve were forbidden to eat. I guess this was a test, I wonder if the tree was created from "the seeds of evil" that Satan created, has something to do with the war in heaven, this was a test for Adam and Eve, they had to chose to follow God, or to fall for temptation of the devil. God told them they would die if they ate the forbidden fruit, but he did not say when. There was also the tree of life in the garden of Eden, God has the tree of life in heaven.
Satan in the form of a serpent, the symbol of evil and deception, dragons serpents, snakes are seen as evil, destructive and deceving in ancient times, he tricked and tempted Eve into eating the fruit from the tree of knowledge of good and evil, and Eve's husband was with her, and she got Adam to eat the fruit from the tree too. When the ate the frobidden fruit their eyes were opened. The serpent Satan told them they would become like God, and know good from evil. Adam and Eve did know good from evil, but their innocence was ruined and the world had fallen because of this sin, they had disobeyed God's one commandment.
When Adam and Eve ate the forbidden fruit, creation was ruined by sin. God cursed the serpent, cursed the ground, the earth, and made humanity suffer from hard work and toil, from an imperfect natural world that would fight him in his struggle to survive. Women would give birth with great pain and suffering, we would suffer from menstruation, from carrying a heavy baby in the womb for 9 months , and go into labor with great pain, so great and troublesome many women died from childbirth in the past. Women would be under the thumb of men for centuries. Men would fear the death the inevitable that took our loved ones away, Satan had the power of death until the Promise came to pass.