Are the Four Living Creatures of Revelation Alien, Human, or Angelic?

There's no Biblical evidence that God created any other alien life-forms. God's plan of redemption is exclusively for human beings. The entire universe will be destroyed and remade so that redeemed humans (not aliens) can inhabit it, according to the text. And the four living creatures are neither angels nor men. They might be the highest form of life ever created by God, ranking above the angelic host, second only to the Trinity!