I'm not replying because I've already explained it. Here, I'll quote myself you lazy bum.

Quote Originally Posted by shinta|hikari View Post
But most of the characters in OPM are parodies of established archetypes, not just funny characters. They take a trope and go wild with it, like super fast ninja whose balls get pawned, super serious cyborg with ridiculous powers but always gets pawned, super bragging enemies that still get pawned, super bully seniors that still get pawned, super gay macho men that escape from prison to rape bishounens, super heroic powerless heroes on a bicycle. This is that kind of show. You just seem to gloss over that pattern and say it's "normal" shounen just because they resemble other shows you've seen (well of course it does, it is parodying them FFS).

Most of the powers and characters actually make no sense and are exaggerated on intention. This show isn't trying to build a logical shounen world and stick to its own rules. The only rule is OPM will OP all.

It is a subversion of shounen. Heroic characters get pawned by villains, only for Saitama, who doesn't really give a fuck most of the time, to destroy said villain with a flick of a finger.
None of the bolded parts are about Saitama. Then you have the silly names of the characters and the ridiculous situations they are always put in. Heck, they even parodied Kamen Rider... Mumen Rider is no coincidence.