How do Jagex verify whether you're the original creator?
If it's based on IP and MAC address of the original creation, then I'm f**ked if I get hacked because obviously both of those have changed in over 12 years.
It's normally fairly obvious when an account has changed hands. We expect people to move around over the years and we wouldn't expect you to be playing from the same PC years after you created the account. So long as you have good links to the account and can provide some good older information, you shouldn't have much to worry about