Note that some sources claim that Stan Lee co-created the Black Marvel, but Lee's first writing credit for a text filler, has been established as being in Captain America Comics #3, with his first comic scripting credit a few issues after that.
There is a teaser for another Super-Slave story next issue, but it never appeared.
All Gustavson credits verified and courtesy of Terry Gustafson, son of Paul Gustavson.
Art credits from Jerry Bails' Who's Who (Henry Andrews 9/24/08).
There is a teaser for another Sub-Earth Man story in the next issue, but it never appeared.
Klein attribution on inks and/or backgrounds by Dr. Michael J. Vassallo, who notes these details as characteristic of Klein at this time:
Page 2, panel 1. Wafting clouds against the moon.
Page 3, panel 3. The black ink streaks at the top left.
Page 6, panel 4. Same wafting clouds against the moon.
Page 7, panel 3. Ditto.
Text with illustrations. Statement of ownership appears at the bottom of the 2nd page.
Only golden age appearance. Next appearance in All-Winners Squad: Band of Heroes (Marvel, 2011 series) #2.
Plot and some dialogue/layouts lifted from the Face story in Big Shot Comics (Columbia, 1940 series) #1 (May 1940).
Credits suggested by Who's Who and comparison with signed work by Davis elsewhere.