If you are a developer or archivist looking at the raw official patch files (like patch 1.09):
Here is a review based on the most common contexts: bloodborne package file
We see that the Moon Presence was originally just a reskinned Dark Sun Gwyndolin from Dark Souls (the rigging files prove this). We see that the Chalice Dungeons were meant to be procedurally generated in the main campaign but were quarantined due to loading times. By reading the package file, we learn that Bloodborne is not a singular vision delivered from on high, but a beautiful accident of cuts, pastes, and compromises. The true horror of Yharnam is not the beasts; it is the hard drive full of discarded ideas that might have been better. If you are a developer or archivist looking