Transfigured character backstory help

I would like to ask on how some one would write / make a (PC) thats been transfigured from their original form like Race, Gender, and ect I want to make a character thats them exploring themselves or just some rich prick that got turned into a goblin.

Just a bit of a random question I know

Some points to answer inside the background

Does the PC remember life before they changed?  If not do they know they even changed?

Does the PC know why they are changed?

Does the PC keep his original species advantages/skills even though they changed?  e.g. all of the stuff granted a dwarven character (original life), but they now look like an orc.

Does the PC have access to the advantages/skills of this new changed species?  Do they have both species advantages?

I would probably personally go for they'd keep mental related stats and proficiency (Intelligence, wisdom, medicine) and take physical stats related to the new race like dex and strength.

I'd also want them to keep their memories 

I'd want to really flesh out the reason why they got turned into a different character species. If this is the classic "Beauty and the Beast" type thing, then there is a lesson to be learned by the character. In that case it was to let strange old women into your castle when you are like 11 years old and your parents are gone. *shrug*

So you want the reason they got transformed. Did they make a deal with a hag? Cross a devil? Enrage a vengeful mage? In this case you'll want to focus on whatever character flaw it was that led to their transformation (greed, lack of empathy, etc). 

However, if they were searching some hidden tombs and encountered a magical artifact that changed them, then maybe the focus is more on learning more about the artifact and how to change them back.

In either case, decide where they are at on their journey. Did they recently get changed? How are they dealing with it? Are they looking for a way to change back? Are they depressed and resigned to their fate? Have they accepted their new form and vowed to make the absolute best of it? All things you  want to look at.

For some inspiration there's the classic Beauty and the Beast example, but also you can look into the story of Nott the Brave from Critical Role Campaign 2. 

I would think the key is how are they changed.  Is it permanent?  If someone casts dispell magic on them do they go back?  Step in a Moonbeam? Brought back from the dead?  If it's permanent and irreversible then it's just flavor.