“Is there anything other than theological doctrine preventing them from both being right? As near as I can tell, the only thing standing in the way of finding common descent from common design is insistence on assuming the literal phrasing of the Book of Genesis is scientifically accurate description of events.”
Saying there is some insistence on Genesis “scientifically accurate” is a pretty silly thing, and just clouds the issue. Nobody insists that Genesis is a biology textbook, telling us how cells formed, or how sexual and asexual reproduction works, or anything like that. It’s much simpler to just say “accurate”. You can either believe the Genesis account is a true account of actual events, or that it isn’t a true account of actual events.
If it’s true, then there were separate acts of creation, and no common descent. If you think that there was only one act of creation, and everything in existence descended from that, then Genesis can’t be true, scientifically or otherwise.
Now, you could say that Genesis is not “true” in this sense, but still believe it has some religious value, and there are plenty of Christians who take that position. It’s not a position I can respect though, because it opens the door to “interpreting away” any part of the Bible that is inconvenient for you.
See post 82 on this thread. Helps to reconcile some of your argument.
I consider that a fallacy of false dichotomy. You either have to believe it's literally true in every aspect, or that none of it is true at all. Those are not the only choices you have.