Theseus is just the son of a king (although some stories have him as the son of Poseiden, it's a bit blurry). Jason was just a dude. There's a bunch of Greek heroes that aren't fully or partially gods and have no divine magic.
LOL. Psionic magic? You mean that totally made up MODERN concept? As in a concept that didn't even exist prior to about the 20th century?
Also note, who really cares about Norse heroes?
Nope. You are flat out wrong here. Japanese heroes have zero concept of ki. That's a D&Dism.
What divine ancestry did Beowulf have? There's a perfect example of a mythic hero. Zero divine. What divine ancestry did Lancelot have? Oh, right. Zero. No psionics, no ki.
Please, FOR THE LOVE OF GOD, either provide an acceptable narrative, or just stop. The constantly moving goalposts, plus your own idiosyncratic views on actual mythology means that we cannot possibly come up with a narrative that satsifies you.
So, again, for the umpteenth time, either pee or get off the pot. Pick a narrative you find acceptable and we'll HAPPILY use that.