I may have mentioned before that D&D, for all its pseudo-historical trappings is actually closer in sensibility to the modern world than anything else. That's probably an inevitable consequence of the game actually being played by people steeped in the modern world - no matter how much research one might do, none of us can ever really be a person living in the 14th century, after all!
Fortunately, the modern world provides an almost perfect metaphor for PCs: the rock star.
Under this model, the first level PC would be any kid who has formed a band and, crucially, has taken the step of actually performing for someone (other than family). They're reasonably common, but they're not that common - most people don't take that fateful step, but equally most people know someone who has at least given it a go. And the motivation is nice and obvious: it beats getting a job, right? (It's also a field that you can at least try to get into and maybe succeed based on raw talent rather than formal qualifications, which is a plus for young people, and especially young people with few other prospects.)
Of course, the majority even of those who do take the step of going out and performing never get anywhere - most bands crash and burn pretty damn quickly.
Higher level PCs are therefore those bands who do manage to keep going, with their level reflecting their relative level of success. At low levels (the Apprentice tier) they remain very much a local concern - people might know about them, but they're hardly going to be stopped in the street. And while there are jobs out there, most of the time they're going to have to find their own work. By and large, low-level PCs really have to make their own opportunities.
Once you get to the Heroic tier, things get a bit easier. Having gotten a few miles on the clock, the PCs are now known and established as adventurers. Suddenly, they have a fame that extends beyond just the few hundred people who happened to be at a gig. People come to them with offers of bigger and better work, and they have a platform to move forward. (And, in the music industry, finding equivalents is easy: just look for any one-hit wonder of the past, and you have a mid-level adventurer. Bearing in mind, of course, that any modern artist who currently has one hit may be on his way up through the mid levels, or might be a one-hit wonder of the future...)
The next step up, then, is the Paragon tier, and those bands that have global fame, and a number of hits to their name, but who don't warrant legendary status. Most of the people who are big in the charts now would fall into this category. (Because the 'legends' tend not to be active much of the time, so tend not to be in the charts, while the music industry has degenerated to the point where it's very difficult to get anywhere unless you're already big.)
And then, finally, there is the Epic tier, which is equivalent to the legends who everyone has heard of - the bands who appear every few years for a massive concert that sells out in seconds, who get dragged out for Olympic closing ceremonies, or similar: Elvis, Queen, the Beatles, the Stones...
There's one other interesting aspect to this metaphor, and it's best represented by "The X-Factor" and its kin: the notion of a patron who for his own reasons wants to manufacture a group of adventurers by pulling together talented people, providing them with the very best equipment and facilities, and basically trying to bypass the whole Apprentice tier altogether (and the Heroic tier, too, if that can be done). Which would basically give us the adventuring equivalent of One Direction. There's got to be some sort of adventure in there somewhere...
