Okay. RWBY. Lots to unpack here.
spoilers:end of spoilers
The Gods of light and darkness are dicks, Salem and Ozpin are more ancient than we ever thought, the current humanity of the world is sort of a humanity 2.0 after the God of Darkness wiped out the previous humanity (And even that didn't kill Salem), it was The God of Light that stuck Ozpin in his cycle of rebirth and told him about the four relics, which will be able to summon him and the Dark God to judge humanity. If they've learned to abandon their differences, then the Gods will remain to guide humanity forward. If not, then all life on Remnant will get destroyed. Salem got her grimm appearance after trying to kill herself by diving into a pit of darkness. This didn't work and she mutated. Ozpin sought out Salem in his reincarnated life, found her and they fell back in love, started up a kingdom and even had a family together. We actually see her capable of being a loving and caring mother even after she became infected with the Grimm's essence. And Ozzie? He was well on his way to uniting all of humanity and fulfilling his promise to the Gods by being worshiped alongside his true love and would've succeeded had he chosen to try and better convince Salem to join him. But after a disagreement between Ozpin and Salem regarding his mission from God of Light, along with Ozpin trying to sneak away with her daughters, there's a breakdown and an epic battle that destroys the castle, likely killing their daughters to. In the end, Oz is left crawling away heavily wounded and Salem is disintegrated....and then she comes right back together and kills him, starting him down the road to where he is now and his eternal war with Salem. Oh and to top it all off one of his other lives met the genie and asked her how to kill Salem but apparently even she doesn't know.
Oh and we also see how the moon got f-ed up: The God Of Darkness flew through it in ancient times, causing chunks of it to rain down on the planet. That didn't kill Salem either.
In short, the heroes are kinda screwed and Raven wasn't lying when she said Salem couldn't be beaten.