Are Cherubs immortal? (as long as they aren't killed)

Likely biologically immortal, and also incredibly resistant to anything that isn’t like, violent damage to their bodies. Calliope and Caliborn can survive under the heat of a Red Giant, and Adult Cherubs can fly through space, so that’s, straight away, resistance to extreme cold, extreme heat, radiation, and no need to breathe. And that’s just their base forms, when they are going to do the do and become giant snakes, they’re practically indestructible.