Something was preventing the Absolute Primordial God from returning home, and without enough strength to leave the World through a space crack, it was forced to stick around. After a while, it took up the position of the First God and amassed a bit more strength, yet it wasn't until the birth of the Original Earthen God that its power truly started to grow.
Eventually, they grew so powerful and connected with each other on a level so deep that they eloped and left the World through a space crack when they knew they weren't welcomed.
The rest of the God's had similar stories, usually having some relation to a Doom Creature. However, just like most Worlds, Utavia refused to allow a Doom Creature to linger for too long, lest it meet its END. Only suicidal Worlds wanted to invite Doom Creatures to stay around. After all, everything was afraid of the END—a state worse than death—the worst nightmare of Gods and Worlds alike.