The rules provided here (Creating a Character, Hero Types, and Lists and Tables) are guidelines. They are designed to create a hero or villain falling into relatively specific, common areas. They are not, however, rules.
If you have an idea for a hero, talk with your Editor. Be specific about your idea, and have it written up as well as possible. You can use the rules here to flesh out the areas you haven’t thought about. Once you and your Editor have worked out an acceptable (by the campaign’s standards) character, do not worry about forcing it to conform to these guidelines.
The only limit to what you play should be your own imagination and experience as a role-player. You may have to resort to Special Immunity, Power Enhancement, or the Magic Spell power to create the character’s powers, or create a power yourself, but these rules were designed to allow any conceivable hero from the most powerful to the least.
That said, do not completely ignore these guidelines. Creating random characters often produces results that you would never have come up with yourself. I have found that the characters I most enjoy playing are those that surprise me in some way, those that manage to diverge from any preconceived notions of what I thought the character would be like—characters who have lives that take over from me.
Unless you have definite ideas about your character, it is usually easier to mold the random creation into something you want, rather than start from scratch and build a character up on your own.
I also recommend that first time players create their characters completely at random, so that they can more fully appreciate the scope of superhero roleplaying. The superhero genre encompasses variety, and this variety can be hard to grasp at first, even for role-players experienced in other forms of role-playing.