Most people read the first four chapters of Genesis and see only one continuous story, as they have been told. Others read the same four chapters and see two distinct stories.
Most people have been taught that Adam and Eve were the first humans on earth – and created in the Garden of Eden – though few have ever seriously studied the account of God's creation and the account of Adam and Eve directly from the Bible themselves.
Most people just assume from tradition that it is a single continuous story, never realizing that it's probably two stories: Creation (Genesis 1:1 thru 2:3) and Eden (Genesis 2:8 thru 3:24), with a summary transition statement (Genesis 2:4-7) and a very long period of time in-between.
This is similar to the way many modern movies start with a flashback scene before starting the main story, to place the story in a setting. In Genesis, the main story of God's relationship with humans begins with Chapter 2, but Chapter 1 gives a flashback of what had already happened before the story begins.
This is the same technique used in the first two verses of Genesis 1, which is a flashback of what happened before start of the main story. The main story, starting in verse 3, is about how God brought life to earth in six creative 'days' (stages). Verses 1 and 2 are not part of Day 1, but preceded it.
As background, we know that the universe ('heavens and the earth'), darkness (dense cloud cover), and water were created before Day 1.
A very long period of time may have passed between verse 1 (God created the universe) and verse 2 (God focuses on planet earth), and then a long time until verse 3 (God starts creating life on earth).
This is the well-known story of God's six days of creation and seventh day of rest.
The creation of humans occurred in Day 6, but the Eden story occurred in Day 7, as explained in the Bible study here on God's creation days.
Genesis 1 says only that God created humans, male and female, but doesn't mention any individuals, choices, or actions.
Genesis 2-4, much later in time, describes named people, their decisions, and their sins.
This is the transition summary between the two stories as clearly stated in the summary preamble: 'This is the account of the heavens and the earth when they were created' (Genesis 2:4).
It is a brief summary of what happened in Genesis 1, the first story: God created the heavens and the earth ... at first, no life or growth ... mist came up from the ground where water came in contact with earth's hot but cooling crust ... then wondrous explosion of life forms ... ultimately, in the final act of creation, God formed man (Hebrew hā·’ā·ḏām, meaning mankind) as a special living creature in the image of God (not evolved) from the dust of the earth (ordinary stuff, atoms, not divine or immortal).
This summary of the first story may have covered a very long period of time.
To affirm this understanding of the time gap, consider these three passages from Genesis 2:
➤ Verse 7 (transition, summarizing story 1): 'And the Lord God FORMED man [hā·’ā·ḏām, mankind] from the dust of the earth ...'
➤ Verse 8 (in story 2): 'Now the Lord God had planted a garden in the east, in Eden; and there he put the man [a human being] he HAD FORMED.'
➤ Verse 19 (in story 2): 'Now the Lord God HAD FORMED out of the ground all the beasts of the field and all the birds of the air. He brought them to the man [individual named Adam] to see what he would name them ...'
There is a time gap between FORMED and HAD FORMED; otherwise, we would conclude that God created man first and then created animals for him to name – i.e., that God created man before He created animals – which we know is wrong based on Genesis 1.
From the transition summary forward, the whole focus of the Bible changes from God's creation of earth and all its life forms to just a single creature: hā·’ā·ḏām (mankind), God's crowning creation and purpose of it all.
The transition summary sets the stage for the second story.
Beginning with verse 8, God places a particular human (named Adam) in a special place (garden) in the east, in Eden. There God meets Adam personally in the first-ever encounter between God and man. God gives Adam the first simple law (don't eat this particular fruit) and says the penalty for violation is certain death (earth's default condition), i.e., no eternal life.
Then God creates a wife for Adam (not from dust of the earth but from Adam's side, a female spiritual clone), the first recorded divine miracle (apart from the six-day creation of the entire universe). Adam names her Eve and tells her about the law. They are now the first spiritual beings on earth ... life-long married couple (one flesh)... knowing God ... accountable to God ... with opportunity for eternal life (if they choose the Tree of Life).
The second story continues by telling about commission and consequences of the first human sin and ends by introducing Genesis 5, which shows how this first couple started a new spiritual family line that ran to King David, then split to Mary and to Joseph, but rejoined in the birth of Jesus about 4,000 years later. As shown in the genealogy chart, Adam and Eve started the human family tree of the Savior. The whole story leads to Jesus.
The Bible clearly states that Adam was the first sinner but does not compel a conclusion that he was the first person.
By explaining to doubters and unbelievers that many Christians believe that the first four chapters of Genesis are two stories, separated by a long time period, a conflict between the Bible and science is eliminated and some of the Bible's lost credibility is recovered.