Thi is killed. The assassination takes place after the first god's slow decline. The forgotten plane Saefi, is able to send minions to find the first god, now living on Rhina, and end the god's long life.
Records show that the gods are not immortal. In fact, all stories tell of mortals rising to godhood and overthrowing the previous pantheons to gain notoriety. Perhaps these are all myths, told to mortals to make them feel special or akin to the gods. After all, no one alive has spoken up to say a different god ruled the sun in their childhood.