Were Adam and Eve the first? Question:  

Reading Genesis, there seem to be quite a few references to some 'other' humans. How do scholars interpret those passages (and more importantly, why do they interpret them a certain way)? Are Biblical scholars sure Adam and Eve were the first humans?

Details:   


In Genesis 1:26-29 it is first described how God created man and woman, without giving specific details: no mention of them being named Adam or Eve, for example, or if there were only two humans that he created.  
Genesis 2 starts by describing the seventh day, which suggests the events are a continuation of those in Genesis 1. However, Genesis 2:4-7 describes how the plants were not growing because there was no man to work the ground, which suggests that Genesis 2 is a retelling in greater detail of the events in Genesis 1.However, that to me is unclear if it's a right interpretation since the events are described in a different order. 
In Genesis 4:14, Cain fears that if he leaves the presence of God, "whoever" finds him will kill him. Who?   
Genesis 4:17-18 lists descendants of Cain. Now, Cain might have had kids with his own mother, but it's interesting to note that all named descendants are male. In Genesis 4:19, Lameh (the last descendant of Cain) is said to marry two wives: Ada and Zillah. Where did these come from? Are the the descendants of Cain as well? Why are they not mentioned in Genesis 4:17-18, then?
And one last interesting bit, Genesis 6:2 mentions how the "sons of God" found the "daughters of humans" attractive. Who are the sons of God? Who are the daughters of humans? Why the distinction? My own uneducated interpretation would be that the 'sons of God' are the descendants of Adam and Eve, while the 'humans' are the others.
It's true that Genesis 1 does not name Adam and Eve, but Genesis 2 does.  Genesis 5 mentions Adam as the first man as well, and the New Testament confirms this.  Genesis 3 ends with Eve being names as such because she would become the mother of all the living.  

Genesis 5 starts with God creating man "in the image of God" and then states that Adam had a son "in his own likeness".  So, Adam was created in the image of God, then the image was a bit marred in Genesis 3, and then Adam had a son in his own likeness.

So, the Bible is in pretty strong agreement that Adam and Eve were the first people created. 

The first son of Adam mentioned in Genesis 5, however, is Seth.  We are told that Cain and Abel were sons earlier than that.  The Bible does not explicitly mention any other sons or daughters of Adam and Eve, although we are told in Genesis 5 that they had other sons and daughters.  The question is, "how many did they have?"

Recalling that their command was to be fruitful and multiply and to fill the earth, it seems reasonable to conclude that they had a large family.  It is also reasonable to assume that by the time Cain killed Abel, they had already had other sons and daughters.  We don't know how old Cain and Abel were when the first murder occurred, but if they were 16, then there could have been quite a few other children around.  After Abel's death, Adam and Eve have Seth, so it seems they are still having children that many years later.

The ages given for those who lived before the flood are quite large, so many conclude that the earth was better suited to life prior to the flood.  Indeed, a cataclysmic flood would certainly have a dire impact.

So, when the Bible mentions Cain's fear of other people, it is referring to other sons and daughters of Adam and Eve and perhaps their grandchildren if Cain and Abel were older.  Adam and Eve were 130 years old when Seth was born, so it's possible that they had been having children for quite a long time (100 years).  This could allow for not only grandchildren, but great grandchildren and even more generations.

The "sons of God" could refer to the line of Seth or others who lived righteously, and the daughters of men could refer to the line of Cain and Lamech, although we can't know for sure.

It is interesting that a genealogy is given from Adam through Noah, Abraham, David and on down 4,000 years or so to Jesus.  This is more evidence that Adam is a real person, because fictitious characters don't have lineages that trace to real people.  So, the Bible presents Adam as a real person who existed in time and to whom all lineages trace back.