There is no physical condition which could permit the survival that I’d find believable, when all other people close to the survivor are killed. Random probability for this would be so small as to be nearly zero. Yes, by our understanding of statistics, there is a possibility – but the odds are against it. It points to another probability, which concerns the existance of this universe without design.

That aside, your subsequent questions and discussion concern the ‘goodness’ of God and the ‘badness’ of Satan.

Believers in God claim that He is TRUTH, meaning that He allows Himself to do nothing which is not TRUTH. TRUTH is exercised in thought, word, and deed in order to be fully consistent.

However, the crux of the title statement deals with ‘good’ and ‘bad’. As believers assert, ‘good’ is a behavior. And, that behavior must necessarily be in line with God’s desires for His creation. Using the English antonym of ‘good’ we get ‘bad’. Likewise the antonym of TRUTH is FALSEHOOD.

According to the literature in the Bible, Lucifer (most powerful angel in this creation) was made with the capacity for exercising ‘free will’. ‘Free will’ is the capacity to make a decision without coersion from outside. A decision, once made, is subject to consequences (cause and effect). Lucifer made a decision to believe that he was as powerful as God and should receive accolades for his position. As a creation, he was stating that he was as meaningful as his creator. This is inconsistent with truth. God cannot abide falsehood to exist alongside truth (call it a cancellation question, or severe perpetual conflict). God had to expel Lucifer from His presence. Lucifer was renamed Satan, because he was rebellious. He was expelled from heaven and confined to earth (where he caused rebellion to spread).

Satan isn’t happy with the constraints imposed upon him. His rebellion continues, and his actions must be contradiction to God in order to be rational. Satan cannot do ‘good’ if God is perpetually going to do it. Satan must be contrary.

God has a plan to recover the earth and restore it to its former consistency with Him. He will necessarily demonstrate His existence, to lead people to TRUTH. If there is no contrast, can people recognise TRUTH when they see it? From the record thus far, they are very challenged in doing so.

God permits Satan to work, on a short leash, to give His leadership and bounty a chance to be recognised. Some people see it, others do not. In order to learn how resist Satan, it is necessary for people (believers included) to suffer adversity. In enduring the troubles, the believer is strengthened. It causes the believer to seek consolation and hope in God’s promise for the future of faithful believers.

The idea that Satan has unfettered freedom to exercise his full fury is a misconception. He is restrained by God, in order that God’s plan can come to completion. God is using Satan (who will suffer separation from God) to support the reclamation of human beings from their sinful (rebellious state initiated by Satan) condition. God loves His creation – that is is His overwhelming motivation. He doesn’t want to see it devolve into denial of TRUTH.

If God is LOVE, then Satan must be HATE – because (like a stubborn child) he resists the parent’s idea. Satan turns inward, thinking of self (instead of outward, which is characteristic of love). In looking inward, Satan denies God (LOVE). Satan wants control for his own purposes, he doesn’t care what others may want or need.