No doubt Kirby was the man but my take is that anyone can write a Thor story as long as it doesn't steal the elements of Marvels version.
I remember All Star Squadron having a Thor as a villain in the early issues.

Kirby's fascination with the gods of mythology is obvious from the earliest days of his career (note his and Joe Simon's "Mercury" strip in Red Raven #1) and his use of the Norse gods specifically goes back almost as far. The Thor character from All-Star Squadron that 'bone mentions above was a villain from the S&K Sandman series, introduced in Adventure Comics #75 (June 1942). In that light, and given Kirby's penchant for revisting the same narrative hooks again and again, that Tales of the Unexpected story becomes less significant.

Cei-U!
I summon the perspective!

Ok but the first story wasn't about Thor so much as a loser finding a hammer.

It's a fairly common literary trope though, so I don't know if you can really draw a direct line between the two. It's a fun fact to be sure, but not a terribly significant one in my mind.

Yeah, I was struck (no pun intended) by Kirby's preservation of the hammer's design. Thanks for sharing this cool discovery, mrp! 

that weird comics artwork is something else. on one level its dreadful. on another level it's truly awesome. could definitely roll with that blown up in a frame in my house

Kirby had an interest in Norse mythology most of his life. He read up on it as a kid.

But another interesting "prototype" for Thor, appeared in Charlton's Unusual Tales #18, from September 1959.

I'm not sure if Stan or Jack read this ephemeral little Charlton number, but it contains some strikingly familiar elements.

Roughly...

A lame fellow named Alvin is no longer in liking his cane, and figures to go buy a new one. He comes across a crafty looking metal walking stick in an antique shop and purchases it from the owner's son for a few dollars. Once in possession of this stick he finds himself fairly healed. Not only that but discovers the stick has miraculous properties that enable it to perform magnificent feats, like shatter boulders or fell trees with a few taps.

The owner of the antique shop realizes his son sold off this miraculous walking stick and scolds him because the stick was actually fashioned from "the mighty hammer of Thor!"

Maybe this is all just a crazy coincidence, and Kirby is on record of not really reading comics (his own or others) from the racks, but creators were always "borrowing" ideas from one another, so maybe Stan or someone else liked the idea of a cane having a relationship with the hammer of the god Thor.