First of all, as an appetizer, this person can't be too weak. In fact, we can't help but see that the gap between heroes and other heroes is actually very large. As an S-class, Genos's own positioning is very high, so it is still very suitable. And the most important thing is that Genos is a robot, and no matter how it is dismantled, it can still be perfectly resurrected. This is very important, and the appetizer can be reused. Genos is a green leaf+a level tester, which is used to test the strength of weirdos and then set off the baldness.
From the damage panel, Genos is definitely an S-class hero, but in the face of weirdos, a set of damage is not filled to death, that is, there is no consciousness of an S-class hero at all, and it is completely the consciousness of a C-class hero. Then Saitama arrived in time, showed off a wave of walking and resisting damage, and took it away directly. The ranking of heroes in One Punch Superman does not represent absolute strength. Our Saitama teacher is one of the biggest examples of hitting the face. Once in C-class, you could put a dragon on the ground and explode the hammer, not to mention other S-class heroes.
Because the protagonist is Saitama, in order to make the plot look good. From the first mosquito girl to the centipede elder at the end of the second season, the events drawn are dragon or near dragon. Even Saitama's filling-and-spinning villain in the street, the sonic Sonik, is the level of an S-class hero.