If Adam and Eve had 2 sons, how did they get married? Who did they marry? How could 6 billion people come from?

Just one of the THOUSANDS of obvious holes in the biblical mess of nonsense. I promise to be 100% open minded if anyone can honestly explain some of these things. Did the 2 boys and Adam all have children with Eve? Why is the book of Lilith excluded from the bible? Why is the book of Enoch not canonized? Since it is in fact the ONLY writing from first hand experience (according to the entire religious community). I obviously have a big issue with the bible. Faith is one thing, but believing a compilation of texts that were not even written for decades (mostly centuries) after they allegedly happened. When I was in elementary school we used to play a game. Everyone would get in a circle, and one person would think of a sentence. That person would then whisper that sentence in the next person's ear, and so on until it made it all the way around the circle (about 20 people). After just 20 people, that sentence would be VERY different, most of the time a completely different sentence all together! But Christians are to believe that those stories (even metaphorically) are the same after that many years and generations? To me, THAT is craziness!