The Cursed God, whom everyone believed had long since died in his era, had his physical body decay, or so it seemed.
But it is not easy for a god-related item to be destroyed with the passing of time; it is more difficult, as these things have more resistance and are sturdier than other normal things.
Gods are considered to be beings out of common sense, undying, having various means to appear again onto the mortal world.
The same is true with the Cursed God; centuries before, in ancient eras, he was defeated when all the human population banded together to face him.
After that, his body parts were distributed among the victors as a memorial, a trophy, and a proof that it was them who had a major involvement in defeating the Cursed God, freeing the land from his massacre.