it depends. guys with looks definitely get a girls attention early on but if your average looking you should have something to make yourself worth noticing. after I start hanging around a guy that has an awesome sense of humor ,can have really intelligent conversations with, or who I just have a lot of fun with will all of a sudden become really attractive to me even though at first glance I thought he was -eh- average looking. If your average looking and shy/awkward around girls at the first impression be prepared to be overlooked. Just know that girls are just as insecure as guys (yes-even the really hot ones who have no reason to be) and they just want to have fun with other people and feel interesting themselves.
first off aren't you immediately judging them by their looks? you are differentiating "average" from "attractive." then you don't say "average" you say "pretty girls" only. so there's your answer. if many of you guys only care about what pretty girls think about your looks, then why the hell wouldn't just as many girls only care about attractive men? why wouldn't you assume that just as many pretty girls only care about attractive men? just a thought.
another point. do you have eyes? do you live under a rock? I see tons of couples day in and day out where "average" guys are clearly getting some. I've seen "average" with attractive with both guys and girls and I've seen couples who were both attractive or "average." its all happened before and it only matters what the girl you're into thinks.
i don't know if I take terms like "average" seriously. its all subjective. what's average in one culture or society will seem extremely exotic and attractive in another. same with individual people. everyones tastes are different. I have friends who think some guys are beyond hot and I'm just like "eh. he's okay." vice versa as well.
i think lots of people men and women may ignore someone they aren't attracted to. my problem is I initially don't ignore anyone. I try to get to know everyone as friends. some guys think if you're really nice to them and joke around, etc. that you must be interested in them or you would respond well to them asking you out. I don't know how many times that has happened to me and its really annoying. maybe some people take that as flirting, whatever. all I know is it puts me in an awkward position. I tend to be slightly standoffish to the guy if he asks me out or says he likes me in this situation. I no longer want to be friendly as I used to be toward him because apparently he takes my signals the wrong way and sometimes I find myself being a bit mean to him actually. nothing cruel but I might cut him off while talking, not look him in the eyes, give off the vibe that I just don't want him around. I hate being that girl. so yes, sometimes I wish I did what many of my friends do and just ignored guys (to a certain extent) who I'm not attracted to.