The 'Humanity, Fuck Yeah!' niche has some truly ambitious fics for this. The 'Mass Effect: Logical Conclusions' series is basically a textbook on this trope, depicting humanity arriving with tech so advanced it redefines galactic politics overnight. It’s less a personal transformation and more a species-wide ascension, focusing on the socio-political shockwaves.
Sometimes the superhuman angle is explored through a single character’s cybernetic or genetic enhancements post-First Contact War. I recall a fic where Shepard, rebuilt after Akuze not by Cerberus but by a clandestine UNSC-style black ops project, becomes a walking strategic asset. The narrative tension comes from them being a weapon that the Alliance bureaucracy isn't sure how to handle, which I found more compelling than pure power fantasy.
Those stories often stumble when the power scaling removes all conflict, turning the Reapers into a trivial nuisance. The best ones use the superhuman premise to ask ethical questions—what does it cost to become that, and how does it isolate you from the species you're supposedly protecting? That layered approach is what separates a memorable read from a forgettable curio.