The problem with your view of personal identity is that this is another kind of essentialism. This gets into the philosophy of identity.

Some trans have pointed out there's no "essence of sex" that makes a body inherently male or female. Being male is simply a label we give to certain humans based on membership of a sex class. There's no core thing that absolutely makes you male or not. That's not unreasonable. It applies to most things in biology. Try defining a cat. Well, a cat is simply a member of the class of cat-like objects, that have gene sequence within a certain edit-distance of a canonical average cat genome, that look sorta cat-like, etc. If there were a continuum of creatures that were sorta-like-cats-but-not-really, we might have trouble defining catness.

The problem with all this is that we can then ask if your idea of "you" might be another example of an essentialist fallacy.

You seem to think there's an "essence of you" that exists apart from your corporeal self. I don't agree. You are your body and you are your personality and your brain and your memories and experiences. That whole cluster of things is you. There's no "core self". If you try to tear the concepts apart in a hunt for "the true you", like a little homunculus at the controls, you won't find anything. Just because we might be able to abstract the network of nerves in your brain and, with our 21st century metaphor, run it on a computer, and it might claim to be you, doesn't actually make it you. You're a whole ecology. Just because you might be able to simulate a thing doesn't make the simulation the thing.

Interestingly people who have been in solitary confinement for a long time, or being hermits without human interaction, also report a sense of their own identity disappearing.

While trans often accuse feminists of reducing women to their genitals I have to ask why you want to reduce people to their brains?