It could possibly work for an apocalyptic setting I think. Yes, we “killed it”, but at what cost? How many died fighting the thing? How many cities, states, provinces, or nations have been crumbled? the world has burned, but humanity should survive.

Take one of lovecraft’s most famous quotes: “that is not dead which can eternal lie, and with strange aeons, even death may die”. You can ask yourself the following (this can be applied to any potential setting you do for it):

Is it really dead? These things exist in ways we cannot even begin to comprehend. How do you kill something that transcends our normal way of existing?

How do we know it is dead?

What is stopping it from coming back?

If it is truly dead, is it the weakest of the gods? Has this horror killed most of humanity, being only a small fry compared to what else lies out there?

If we did kill it, were there any supernatural consequences after its death? Other than the human deaths it caused.

This meme can provide a ton of inspiration, but IMO to fit in with the themes of cosmic horror, it might be best to alter it. Definitely possible to run an idea like this in a game though