The Ironborn are born from...?

Right. So the issue with the idea that they arnt descended from the firth men or Andels is that that means there ancestors or ancestor ended up on the shitty little island chain and accepted his face of being... on a shitty little island chain with no resources. Like. He landed on the Iron Islands and was like "This is a good place to settle. And not the most likely massive land just across the way that I can see the mountains of"

I'd go with the theory that hes/they (We'll go with He, the Gray King) is/was of the first men
and he was a fishermen, and his tiny boat got pulled out to sea and was wrecked by storms, Or maybe a Sea Dragon.. or combo. and he very nearly drowned but got washed up onto the Iron Island.

And he credits the god of the sea. The "Drowned God" as saving him. Because First men worship old gods, gods of nature. (Perhaps once the Old gods had names of sorts. And the weirwoods forests / godwoods were simply sacred places were small shrines were built. But over time the gods became the trees and the trees became the gods, as people forgot.) so its not that much of a stretch to think a man whos lively hood is water based, would pay homage to a god of the water/sea. And credit said god for his continued life after nearly dying.

Of course, this was all so long ago. That The Ironborn cant actually be considered First Men.

Or... well. I got a few more stories. Ranging from they are actually decedents of escape slaves brought over by the Andals. (not that the Andels kept a lot of slaves) but that would explain why they are called Ironborn in another fashion.

Another is that they are decedents of the people from the Island of Ib who had originally been living in the Andals before the people we know as handles came and pushed them out. - Fleeing to the sea, the landed in westeros around the neck, and kept heading west, trying to get out of the marsh lands, harassed and pursued by the First Men who lived there, who considered going after them until the reached the Salt spear where they took to the sea again.

Hpwever, they never made it very far before storms over came them, or as I said, maybe there was also a sea dragon involved. who knows, and the survivors washed up on the Iron islands.

I might be working on something with this...