the first two cartoon heroes I remember (that weren't from comics) were the Mighty Mightor and Samson and Goliath.
made by Hanna-Barbera in for NBC's Saturday mornings in 1967, it featured 18 episodes in a half hour format. I must have watched it, but my main memory of it comes from a coloring book that I had.
Samson had magical gold wrist bands that when slammed together turned him into a "peplum" hero of immense strength and power. he would slam the bracelets together a second time and his dog would turn into an immense lion, complete with eye beams and razor sharp claws.
Captain Marvel, once he had merged with perpetual sidekick Rick Jones (in looking at that Wiki entry his middle name is "Milhouse"? the fudge is that? I mean really, how stupid. but I digress.) and the whole thing, combined with Mightor, is pretty much the overrated He-man's motif.
in the course of 18 episodes, Samson and Goliath took on giant monsters, statues come to life, aliens and spies. I wonder who at Hanna-Barbera thought of the concept, since the whole peplum movie fad had run it's course a few years earlier. his hair isn't even that long to look like the biblical Samson! still, it's an action packed show and what kid wouldn't want a giant lion to ride?