Hi faitheist and welcome.
Are we all descendants of Adam and Eve?
The answer is no. The story of A&E is a myth. As NoNukes points out there are many other creation myths with equally valid claims to accuracy.
Science tells us that we all have a common ancestor but what reason is there to believe that it might have been any character from this particular creation myth? I mean why would you even consider the possibility? What evidence do you have that would support such an idea?
You are referencing an allegorical creation myth written 4 or 5k yrs ago. What part of your reality today would lead you think that it was actually true?
I asked the original question not as a Bible study question but as science question.
There is nothing outside of the bible for science to investigate regarding this question.