How do you know Terri was her original person. I’m sure most close to her would have disagreed.
i’ve known people ravaged by brain damage and they are not their “original person”
She should never have been murdered but your argument isn’t strong.
Terri's soul was still there--in some sense, she was still the same person and may have still had some of the original memories. If the brain of someone like Terri could be regenerated with her own stem cells, she probably wouldn't be the same as before. However, none of us is the same person as we were one, five, or twenty years ago. All of us exist on a continuum with the person we were in the past--and so would be the case with a severely brain injured person whose brain could be repaired, they would still be on the same continuum.
OTOH, once the brain dies, the person is gone. Growing a new brain in that body truly would be creating a new person--and in unethical fashion, since that new person would be a child in an adult body, and would have a seriously truncated life-span as compared to children who start off in the usual way.