We didn't descend from apes. We both came from a common ancestor, but apes split off millions of years before.
Genesis is not allegorical. Allegory is specifically where every symbol means something else.
There is hardly any allegory in the Bible. A long time ago, there were those that interpreted everything as an allegory, but that just did not hold water.
Similarly, a literalist translation does not hold water.
I think the concept of original sin is misunderstood by the literalists. I simply believe Adam is a story of how some ancient peoples tried to explain their existence. I think there are some spiritual lessons there, but they may not be exactly what you interpret them to be (or what your pastor thinks they are).
The Bible is a book about the Spirit and the Kingdom of God. If you are an engineer, you may be looking for too much precision. Nothing is certain. God is not about to reveal all his secrets. A God that did would not be much of a God. I know that I make mistakes (sin) every day. To me this is a continual fight between my animal nature and my spiritual nature. It is spiritual warfare. If you reject the fact you have come from animals, you are endangering your spirit, for you will not recognize the battle until it is too late.