Frisk...Isn't the hero of the story

They....

Kind of get everyone in the right place and the right state of mind for everything to happen

at least in no kill neutral/pacifist

The real hero is Asriel

(tying back to the delta rune and its significance...)

since they're both the "angel" who's seen the surface

and the angel of death

It's even right there in his name pfff

So really Frisk is the facilitator/helper guide person

he just had to get Asriel to a point where he could fulfill his role and really become the hero he was meant to be

before everything got FUBAR'd