Kirby never explains how Darkseid gets his powers or his trademark look. But he does detail his rise to power. Uxas (Darkseid) was the son of Hegra, queen of Apokolips. Uxas had his friend/lackey Desaad poison the queen. With her death Uxas became Darkseid, ruler of Apokolips.
John Byrne went into more detail of Darkseid’s origin. Uxas had a brother named Drax. Drax was chosen to enter the infinity pit and wield the Omega force. Uxas tricker Drax and seemingly killed him in order to take his place and gain the Omega Force. The infinity pit gave Uxas power but also transformed him into the craggily skinned version of Darkseid that we now know. Drax survived Darkseid’s attempted murder and became The Infinity Man.
Yeah, it seems pretty obvious to me that he's kinda like the protagonist in the movie "Jacob's Ladder" in that what he thinks is his life is actually his (literally) existential crisis as he could either succumb to death or make it out... and I expect things to get more surreal and dark.
He's still in the process of figuring out the nature of the trap he's in and how he's going to get out of it.
This really can't be overstated enough. Morrison has made it clear that all New Gods depictions are all equally canon and non-canon. None show the full glory of the Gods, only shadows. Darksdeid can be a simple farmer, the proprietor of the Dark Side Club and the brother to Drax simultaneously.
And this is exactly why I love Grant Morrison. As a writer myself, this would be how I would depict any kind of god character. In that sense everyone wins. The true form of the New Gods exist in the god sphere. We saw Darkseid's true form as depicted in Final Crisis and Seven Soldiers. And Multiversity completely clarifies how the gods exist in different facets of themselves across the multiverse. To some degree, Neil Gaiman addressed this multifaceted existence with Dream in Sandman: Overture. I think that kind of thinking could be applied to the New Gods as well.
All the more reason I would love to see Death of the Endless pop up in Mister Miracle.
If I'm not mistaken, it was the 1995-1997 New Golds volume Byrne did.