I started with Superman #1 (which premiered June, 1938) and read up to issue #9. I have to say that this version of Superman is quite a bit different than the silver or bronze age depictions. In these early issues, Superman's origin is different, his powers are different, and his personality is different.
His planet of birth, Krypton, dies of 'old age.' A friendly scientist -- not his father -- places the infant Superman into a space-ship, sending it to Earth.
A passing motorist discovers the space-ship with the infant Superman and places the child in an orphanage. There is no mention of Ma and Pa Kent.
As an adult, Clark Kent works for the Daily Star, not the Daily Planet.
Superman can't fly, doesn't have heat-ray vision, doesn't have x-ray vision. There's no mention of super-breath, super-speed, or any of a dozen other abilities that he would later employ. There's no mention of him being harmed by kryptonite. He's strong, capable of bending steel bars. He can leap 1/8 of a mile! And he's bulletproof, with only a 'shell-burst' capable of piercing his skin.
Oh, and this Superman is a jerk, doubtless because he grew up in an orphanage... and by the way, Lois is a jerk too! Superman spies on people -- a lot. He's a bully, who terrifies ordinary citizens as well as crooks, and he casually beats up on people, usually mocking them as he does so.
Notes: On the first page of issue #1 it is stated that Superman can leap 1/8 of a mile, or 132" in Mighty Protectors terms. I therefore tried to get his leaping distance as close to this number as possible.
Superman 1938 Image
Superman is a Spy
Superman is a Jerk I
Superman is a Jerk II
Superman is a Jerk III
Lois is a Jerk Too
Superman #1 Cover
Superman is a trademark of DC Comics. Mighty Protectors is a trademark of Monkey House Games. This write-up is by B.K. Adams.