I'm changing her a bit. The reason of why she is so old is because she is actually from a species I call Stardust!
Stardusts are very opinionated and violent to those opposing, causing them to massacre each other. Your opinion/alignment changes with your appearance.
Stardust's change their features and Immortal said "all of you are stupid, bye, see you never" and then did never see any of her kind again.
She saw humans, who lived with another species that told stories of powerful and gorgeous creatures. Humans misinterpreted dragons as humanoid creatures, and she did too.
Longer necks, strong horns, strong carapace, gorgeous and angled eyes.
Her horns are actually antennae, malleable, but they can stiffen to impale others.