The MC or the main character means a protagonist as shown in the title (not the entire book though, just the volume) or the person the story follows. In some cases, there can be lots of main characters (like the MC of that part dies then the legacy lives on to be the next MC) and also the MC usually becomes OP (overpowered) (not criticizing) and blah, blah, blah
well, not in this story! this story follows the life of an ordinary guy doing ordinary stuff.