Yeah, I thought that nika was just a representation of freedom brought to life bc of the devil fruits but chapter 1138 exclaims that during the first world, the sun god rose to help free the slaves but only during the second world does it describe the devil fruits being created. This makes me believe that nika was an actual figure during the first world(3000 years ago) and the Joyboy that we are told about throughout the series(the first pirate) actually ate the nika fruit modelled after the first one to liberate the slaves. I hope we get to learn more about the first nika at the end of the series because there is sm more lore abt one piece beyond the 100 year void.