The lower levels are absolutely not all disasters, you just have to alter your driving style a little.
Think about it this way, if you were driving on a public street where you knew 40% of the people were VERY DRUNK, you would drive a little differently. For many rookies, this is likely their first serious shot at sim racing, and they just aren't used to the controls yet. Many won't practice and will just jump in a race.
It's like they tell you when riding a motorcycle....."pretend that every car on the road is out to kill you." You ride according to that and you'll be much better off.
So go into rookie races assuming that every single person is going to crash at least once. It won't always happen that way, but sometimes it will. So drive very defensively, don't make daring passes, if someone is right on your bumper, let them pass by pulling to the edge of the track and slowing slightly. There's a good chance they are pushing too hard and will crash and you'll get your spot back anyways.
Higher series are a little cleaner in general, although it's not always the case. Hell, watch the ISR 120 Minutes of Thunder Split 2 pileup, that was a bunch of very fast and very skilled drivers.
Just relax, keep a cool head, and you'll do fine.