Q about creationism/the Bible

[Brom]

OK I'll admit that I don't know much about the Bible. I'm non-religous and was raised that way. I just wondered if someone who knew more than me on the subject could clarify a problem I have with it.

If one takes the matter of Adam and Eve to be true. It is my understanding that these were the first two people on earth, and the mother and father of humanity. Now if these were the first two people from which all other people were born, wouldn't that indicate a ridiculous amount of imbreeding that went on to form the 6 billion person population we have today?

Were there actually more people originally put on earth? Is the story of Adam and Eve considered to be false? Do they not believe such things as imbreeding exist (I thought it was a sin)? Can somebody shed some light onto this for me?