It is estimated that the total number of people that have ever lived since Adam to the population of the world in 2017 is approximately 108 Billion! Now how many do you think have gotten saved through the Cross or the OT Law (Paradise). Most guess 1% or less! And YHWH lost his highest in creation Helel (Lucifer in Latin) plus one-third of the angels and all of the Nephilim offspring of women and fallen angels from Genesis 6. That's pretty pathetic for a score card. God has said that He is not willing that any should perish, but all come to repentance. But since God has the three Os (Omnipotence, Omnipresence, and Omniscience) then clearly he could appear to everyone and bump that number up to 99.9%. He has chosen not to. We have free will to accept the work of salvation or reject it, but there should have been a better way to reach more people. Let Bible dude tackle that. Sin entered through Adam at the Tree of the Knowledge of Good & Evil. So the thinking is that Jesus became the second Adam (the Word made flesh) to be crucified on another tree (the Cross) to accept the sins of the world. That is absolutely correct, but not very efficient. There is no salvation for angels because they were created holy, saw God as he was, and although having the ability to chose, had no right to for they were all created as ministering spirits. Man was created naked and of flesh which was fallible. They were simply created innocent, not holy and were lesser creatures but with free will.

* shortening of mutants. Demons are NOT fallen angels but their disembodied offspring who live on earth and seek to inhabit a body, human or animal to regain the 5 senses. Falling angels have permanent spiritual bodies and wings and inhabit the cosmos. They have their bodies intact.
** Hell is only a holding cell of darkness, wailing, regret, separation from all life and God. After the Second Judgement the evil dead of all time and Helel and his third with all demons will be cast into the Lake of Fire which is the second death. The smoke of their torment (varying degrees) rises up forever.