Almost all heroes are both ordinary and extraordinary. It's virtually impossible to find a hero story that doesn't deal with some combination of the heroes ordinary nature and ordinary challenges and the heroes extraordinary nature and extraordinary abilities. This is inherent to the whole concept of heroic ethics that resonates so powerfully with people. If the hero is merely extraordinary, then the hero is not someone that can be related to your present position. A purely extraordinary hero is too remote to be idolized and his problems (if he has any) are too alien to see in them solutions to your own difficulties. A purely ordinary hero is not worthy of emulation and does not inspire the audience to strive for a more heroic mode of living their own life.
Virtually every mythic hero story begins in the same way.
1) The hero possesses abilities which are unrecognized or unfulfilled, however, the basic core of goodness, courage, and honor are made known to the audience.
2) The hero faces some extraordinary difficulty.
3) The hero finds the means to overcome this difficulty.
I believe the fundamental question is flawed.
Almost all heroes are both ordinary and extraordinary.
<snip>
To me, the real question is not, "Is the hero ordinary or extraordinary", but, "Where in the hero journey do you begin the game?" The D&D model generally assumes that you begin the game at the very beginning of the hero journey.
<snip>
... on the whole I like to start as seemingly ordinary individuals with extraordinary destinies. Now, whether the ordinariness is a skin deep covering of something extraordinary, or whether it lies hidden at the heart of someone superficially extraordinary is for me a more interesting question.
4E seems to be built on the idea that you must be "above the curve" of everyone else (there's something that makes you stand out from the commoner on the sidewalk) and does not seem to support the "ordinary person in extraordinary circumstances" model very well at all.
Virtually every mythic hero story begins in the same way.
1) The hero possesses abilities which are unrecognized or unfulfilled, however, the basic core of goodness, courage, and honor are made known to the audience.
2) The hero faces some extraordinary difficulty.
3) The hero finds the means to overcome this difficulty.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.