Actually, the words “terrestrial” and “celestial” are derived from Latin — “terra” and “caelum”...
Hmm I wonder why Paul would have used those words. Maybe it was the translators. What do you think the original Greek was?
Regardless - the doctrine of three degrees of Heaven is found nowhere in the Bible. Earning your way into one of those degrees is not Biblical.
Mormonism isn’t Biblical. Sorry.