Before there was a Marvel Comics Publishing house, there was a company called Timely Publications. The very first comic they produced in October 1939, Marvel Comics #1 would star The Human Torch, Namor The Submariner, the Angel and Ka-zar the Jungle lord.
Later, they would change their name to Timely Comics and publish more well known characters such as Captain America and his sidekick, Bucky. Eventually, in 1961, Timely Comics because Marvel comics and we know how well that turned out.
Due to the historical nature of Timely Comics, I felt it was worth keeping an eye out for any 1st Appearances.
Archer Armstrong 8 1st Ivar Time Walker Appearance Barry Windsor Smith
Time Remaining: 4d 17h 54m
1ST APPEARANCE OF STEVEN UNIVERSE IN COMICS ADVENTURE TIME 2013 SPOOKTACULAR
Time Remaining: 4d 21h 32m
Buy It Now for only: $11.99
KURT BUSIEKS ASTRO CITY NO1 2 ALEX ROSS COVER 1ST APPEARANCE OF TIME KEEPER
Time Remaining: 17d 22h 14m
Buy It Now for only: $1.25
1ST APPEARANCE OF ADVENTURE TIME WITH FINN JAKE IN COMICS RARE FCBD
Time Remaining: 18d 5h 10m
Buy It Now for only: $20.99
ARCHER ARMSTRONG 8 1ST APPEARANCE IVAR THE TIME TRAVELER
Time Remaining: 22d 11h 3m
Buy It Now for only: $10.49
Adventure Time Spooktacular 1 VF NM 1st Appearance Steven Universe
Time Remaining: 22d 11h 26m
Buy It Now for only: $14.99
Captain America 6 Out of Time 1st Appearance of The Winter Soldier 2006 VF
Time Remaining: 29d 9h 9m
Buy It Now for only: $19.99