Very interesting. That's well-spotted, Peter.
I've been trying to find some of the other covers, using the galleries at DC Indexes. The second cover from the right in the second image is Dell's Flintstones #6, from May. The one next to the Amazing Fantasy cover in the first image might be a Harvey comic, but I can't see it in the galleries.
I didn't know this, but it seems the month the new superhero features were launched was also the month the first Gold Key comics went on sale. I would think Marvel's publisher Martin Goodman knew that was going to happen.
I The one to the left of the Journey into Mystery cover is Dell's Thirteen #4, from June.
I also found it quite fascinating to see it as a brand new copy of AF 15, before it would get hit with "Marvel chips."
We talked about this here:
Wow! That is AWESOME!
The rightmost cover in the lower image is another copy of Thirteen #4.
Was Burgess Meredith ever young? He looks old even here!
He even looked kind of old in Of Mice and Men in 1939.
The comic to the left of Amazing Fantasy #15 in the upper image is Dell's Margie #2.