The battle is eternal, you are right about that, but its not the battle you think, you are not the protagonist in the most important cause in human history, you are just a lowly soldier marching to the beat of fear, of ignorance and hate.
Sometimes the darkness wins some battles, when everything good we’ve achieved is brought to ash, stories of that are woven through our mythology, the Flood, Babel, Atlantis, the Fall, Ragnarok, even Sodom and Gomorrah. Your storytellers have always tried to make it out that they are stories of punishment, of victory of good vs evil, but they can’t hide what they really mean.
The stories are not about destruction and punishment, they are about change, death and rebirth, which is a very human concept.
When the first city fell, if your ideas had their way, we would have never thought about learning or progress again, but within a hundred years of each other Egypt, Mesopotamia and the Indus Valley civilisations blossomed into life. Even when you destroyed Rome, less than 2000 years later, using a shoestring calculator and hydrogen/oxygen deathtrap this little fallen species visited another world.
There will always be the ignorant, the fearful, and sometimes they might find ways to bring us down. But for the next 1000 generations, anyone who can build a telescope and look up into the sky, will see a flag flying there, left by a people who took the forbidden fruit and went to the stars with it.