Wow, that is SO unusual...and such ROTTEN luck for you. I've known countless snakes for decades & never had one as clueless as yours seems to be.
It may indeed be an defect from inbreeding, assuming she isn't starving? It may be that her sense of smell is poor, for whatever reason, as she appears
to be basing her decision to "feed" on your hand by just your body warmth & perhaps motion. (warm & wiggling = prey to her) Are you SURE you're
feeding her enough???? As a snake grows, you need to size UP her prey...what are you feeding her? (pix of her AND her typical prey might help?)
You're a beginner with snakes and you'd be so much happier (feel comfortable) with a snake that matches your experience. It's not for me to say, but it
would make total sense for you to swap snakes with someone who has a reliable (boring?) "pet" and the experience and desire to work with yours. Or
just re-home yours & start over...(and NOT with a king snake either, LOL! They can be pretty stupid about hands sometimes too...)
In fact, if you live anywhere near me (I won't ship), I could fix you up with a perfect pet snake (just not a BP).
One other thing comes to my mind though: have you had her stool checked for parasites? If she has them, that could make her hungry all the time, since
she's sharing her food. But short of that, you somehow picked a totally wrong snake.
As far as making a snake let go, a bit of alcohol is often recommended...though I've never personally used it. You could try rubbing it on your hands, so
they smell of it when you try to handle her. I'm impressed that you've had her this long, under the circumstances.