I am having a bit of trouble figuring out what you mean. By "ball of hot rock" (meaning the inside molten part of the Earth) with a "thin crust" (the part of Earth that life lives upon), how are we sandwiched between the "ball of hot rock" and the "thin crust" when we will on top of the "thin crust"?
Or am I getting you all wrong?
And for the rest, our standard of normal is indeed living on Earth. That's the only thing we have ever known...ever...unless you count the space missions but I would not call that "living" in space but more as visiting space.