What's simpler depends on how one's mind works.
Too "rules light", and it doesn't click for some people. RISUS might be that for you, even with somebody's "supers" supplement -- but it's just a little download to find out.
Four Colors, a.k.a. 4C, is a "retro-clone" (using the term loosely) of TSR's Marvel Super Heroes RPG.
Now, one thing that made the original easy for me was the many write-ups of familiar Marvel characters, their powers and equipment. After seeing how, say, Spider Man or Quicksilver could be represented, I had a better grasp of how to depict my own and other's creations. Most of the time, I used the "modeling" approach to making characters, in which we write up whatever is necessary for fidelity to the concept (rather than rolling on tables or spending points).
Also, there were Basic and Advanced versions. The latter added a lot of (IMO) distracting chrome, some of which may have crept into the 4C rulebook. (It also left the cool chrome for magicians to a supplement.) However, I think 4C also includes some additions to the universal resolution table that I consider nifty and easy to use.
The original Basic set also featured Marvel-ous instructions and commentary from Spider-Man, the Thing, Mr. Fantastic, Doctor Strange, and others. This made the text fun to read (not always a characteristic of technical writing) while remaining eminently clear (ditto). It also came with big, full-color maps and counters, and a short scenario, but a PDF is not as convenient as a box for packaging such goodies.
Anyhow, "4C" is another (somewhat larger) free download maybe worth a look.
There is another, lesser known Four Colors game (by Cynthia Celeste Miller, IIRC) devoted to "Golden Age" (1940s) role-playing. It is also fairly simple.
