Questions about why God didn’t start humanity over right away by destroying Adam and Eve instead of waiting for the flood, whether another fall will be possible in the new creation (and what that means for our free will), and why God didn’t make us “fall-proof” from the beginning.

Why didn’t God start humanity over right away by destroying Adam and Eve if he knew he was going to have to destroy an evil generation with the flood later on?

In the new heavens and earth, will another fall of humanity be possible, and could this create an infinite loop of creation and fall? If not, does this mean there will be a lack of free will in the new creation, and why wouldn’t this “fall-proof” design have been God’s original choice for creation?