Threads drift, no worries. It's an interesting subject. Perhaps start another thread on it?
I see a number of reasons to not see them as connected. One is that the Documentary Hypothesis sees them as coming from separate traditions. I know there has been challenge to the DH but I'm not well read on that subject.
Another reason is that in Genesis 2 we see a man, Adam, made and then animals are brought to him. If this refers to an original creation of animals then it contradicts Genesis 1.
Also there are other people in existence besides Adam and Eve and their first children. This is made clear when later in the story Cain is driven away where he marries a wife. Simply said, nowhere in Genesis 2 are Adam and Eve said to be the first or only human beings.
I'm not well read on DH either. It would not be surprising to me to learn that what started as oral tradition had some warping. Though to separate the Genesis account would contradict Jesus assertion that it was written by Moses. As far as the age and authenticity of law scripture, you'd have to take it up with Creation Minostries, they do have a big rebuttal page on DH.
As far as I'm aware the bringing an animal to Adam to name was similar to the flood for literalists. He went to religion all animals and non-regional animals came to him. Again I'm not very read up on that particular contention.
Cain's wife, however, was believed to be one of his younger sisters some hundreds of years after. Literalists reason that humanity being closer to perfection would not have suffered from incest at that time (or much of anything, hence the long lives).
I do not deny that there are many contradictions in the bible. But I still believe the overall narrative intent and the belief of the authors (including Jesus) was a YEC story.