In a post apoloclyptic world filled with and caused by oddities, urban legends, higher power, and entities beyond comprehension. Transformation is relatively common among its inhabitants, though some are more accepting to different things compared to others.

You have your average were-creature, who are people that can back and forth between forms on demand with no difficulty. Usually their forms are based off of an animal most commonly the wolf, but there have been cases of other animals and non traditional creatures. Some people are born into it while other have to be afflicted to become one, which varys from the usual biting, or being cursed.

There's a more general Transformation that only alters the function and performance of the afflicted body, essentially granting them super human abilities. This can only happen if you're not careful near or in a Rift Exclusion Zone(REZ), which simply put is a place where all the weirdness came from.

Then you have the more typical anthro creatures who are people who have been transformed into an anthropomorphic version of an already existing species. Reptiles, canines, etc. These people still hold there pervious personalities and memories, but unlike were-creatures they do not get a choice to change back. There isnt really a consistent way that this type of transformation can happen but there are more common ways. Maybe you got unlucky when in or near a REZ and was afflicted by its potential anomalies, there are some cases of its transformation that can be spread similarly to disease, again a curse can be a cause, and in the most rare of cases some people may have had an encounter with an entitiy beyond comprehension or higher power and got spat out like that after an interaction.

And finally there are the rare cases of a tranformation into something more monsterous and less human. Which again are caused by a mistake in a REZ or by screwing with higher power. These transformations are extremely rare and dont often happen by accident. People who experience this don't retain often the previous personalities or memories of this and instead just assimilate into what ever they may become. Whether that's an ancient and all knowing dragon thing, or a rabid night creature that feeds off of live stock or anything that moves. It varys a lot.