Most games do require the creation of some sort of character, because of various stats that the characters have. Without some sort of number to represent skills, there's no way to determine success or failure within a dice-based system.
That isn't to say you can't "be yourself" - there's no need to go into trying to be an Ork Rigger or something in Shadowrun, when you can just be a human with no magic or anything named Fig Newton. I played simple warriors and thieves for years in D&D before moving on to magic-using classes (bard and paladin primarily, for those wondering), and while I'm not too familiar with Shadowrun yet I'm sure there's some pretty simple ways to build a character that won't take much effort to play.