The Garden of Eden
The story of the Garden of Eden, regardless of the chronological timeline, begins hard on the creation of the earth. It introduces the beginning of man on earth.
26 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. 27 So God created man in his own image, in the image of God created he him; male and female created he them. (Genesis 1:26-27)
In reality, of course, the story of the Garden of Eden is one of the most complex stories in the Holy Bible, and there is nothing simple about it. It is a story about conflicting commandments, agency, opposition, consequences, the purpose of life, and freewill.
Our first parents were married by the Lord, ruling out the idea that sex was the original sin.
21 And the Lord God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof; 22 And the rib, which the Lord God had taken from man, made he a woman, and brought her unto the man. 23 And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man. 24 Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh. (Genesis 2:21-24)
The first commandment was to multiply and replenish the earth.
8 And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth (Genesis 1:28)
The irony is that they could not multiply and replenish the earth because they could not have a sexual union until after the fall.
6 And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat. 7 And the eyes of them both were opened, and they knew that they were naked; and they sewed fig leaves together, and made themselves aprons. (Genesis 3:6-7)
Before, they had walked freely with God when he came to visit. Now, recognizing they were naked, for the first time, they were ashamed.
8 And they heard the voice of the Lord God walking in the garden in the cool of the day: and Adam and his wife hid themselves from the presence of the Lord God amongst the trees of the garden. 9 And the Lord God called unto Adam, and said unto him, Where art thou? 10 And he said, I heard thy voice in the garden, and I was afraid, because I was naked; and I hid myself. 11 And he said, Who told thee that thou wast naked? Hast thou eaten of the tree, whereof I commanded thee that thou shouldest not eat? (Genesis 3:8-11)
