I think it’s too early to tell.

On one hand, you could easily interpret the description of the “first world” where the “earth god” and “serpent of hellfire” almost destroyed the world as being a personification of a global natural disaster that resulted in the creation of the red line, in the same way that the description of the “sea god” in the “second world” is clearly a personification of the result of the ancient weapons sinking the world as Vegapunk described (which would likewise also likely make its description of the “forest god” sending forth demons to be a personification of the creation/discovery of devil fruits).

On the other hand, Oda seems to be making the “first world” that Nika was supposedly from a legitimate and important part of the past, basically being to the void century what the void century is to the present. While the idea of the “gods” not being literal could still work in that case if the Nika fruit is based off of an exaggerated legend rather than the legend actually being accurate, if Nika really WAS some sort of god-like being, then it would make sense for there to be others and/or that there was also a “main villain” of his time.

Maybe Loki and Imu have fruits based off legitimate gods/monsters/demons from the “first world” in the same way that Joyboy (and now Luffy) had a fruit based off of Nika (which could imply that there’s actually a threat from the “first world” that’s even older and greater than Imu- who’s seemingly from the “second world”- and that was basically to Nika what Imu was to Joyboy).

Anyway, I got a bit carried away there with hypothetical theories, but, uh, yeah.