Adam and Eve were the first to people on earth and they had no idea what evil was and god gave them all kinds of plants with fruits they can eat from but he put one tree in the garden of Eden call the tree of knowledge of good and evil and told them they can eat from any of the trees but that one, and then Satan who is a fallen angel tricked eve into eating from the tree of knowledge of good and evil and then she gave the fruit to Adam as well and then God banished them from the garden of Eden and now people can die and kill others and commit all kinds of sins. so in the end God gave people free will because you cant force someone to love him and Adam and Eve fell for Satans Lie.