I wonder.
Is a significant population portion of 1st level commoners unrealistic in a dangerous area?
On the surface, this sounds true, but let's consider two things:
1) We are talking a fantasy world where magic exists (then again, real monsters exist too).
2) In real world medieval cultures, was most of the population relatively unskilled (i.e. low level) peasants?
I think the answer to #2 is yes. Granted, you could have a city of 100,000 people where some significant portion of the population were artisans, merchants, militia, clergy, tanners, etc. and not common laborers.
But, cities had to be fed and it is generally accepted that 9 people out of 10 (more or less) in medieval cultures had to be supplying the food.
This also depends on what you consider "relatively unskilled". I consider this to mean that even if you do not have a lot of skill points in a skill or group of skills, you can take 20 (or take 10) with many skills and adequately perform a job.
It doesn't take that much skill to fill a bucket up with water, to feed chickens, to hoe a field.
Neverwinter Nights handles this fairly well in that unlock attempts (at least by low skilled characters, do not know what happens with high skilled rogues) are always take 20. Hence, you always take the time out to try your best.
In DND, most job-like menials skills should not be done in a hurry, rather they would be done in a reasonable time frame and fashion.
So, I think yes is a relatively valid answer to question #2.
Getting back to statement #1, how does magic and monsters affect the equation?
It depends on what monsters you are talking about and what levels of magic.
If you are talking about marauding type monsters like possible Orcs, then a small amount of magic (or a small team of low level NPCs) might be enough to discourage them from raiding settled areas and have them settle on raiding other monsters or even forest creatures.
If you compare this to inner-city gangs today (also a dangerous environment), you do not tend to see gang wars every day. They each pick out a territory and stick to it (for the most part). I think the same would occur for Orcs and Goblinoids unless it was a hard winter or something.
Also, since food is one of the major requirements to survival, it is also possible that commoners would strike deals with marauding monsters to actually feed them.
If you are talking larger more powerful creatures, then even a small community with a bunch of 3rd to 5th level commoners would probably not be sufficient to protect the community. Instead, communities would tend to wall up or hide to minimize the frequency of powerful encounter occurrences. Given that, it would seem that even low level commoners could hide behind walls or within a forest just as easily as slightly higher level commoners.
So, all in all, yes, the chance to survive with higher level commoners would generally be greater (assuming that they do not get complacent since they are higher level). But, it is unclear that it is a definitive fact that lower level commoners would be unable to survive.