First, you do not know what other people are doing and some kids will say they ran a lot less than they actually did or they are playing other sports (or lifting).
Second, you could be in great shape and not using proper race strategy. This is hard to explain as your pace will be different that others. In high school you will find that many people just try to keep up with the best runners until they die. That will not work for everyone. In fact it will only work for a very select few. What you want to do is find someone you know you might have a chance to beat. Merely keep him with in 10-30 meters the whole 5K. When other people start to "comeback to you like magic," then you will know that you have hit it right. Not everyone can be The Powerful Front Runner. Watch races on You Tube.com. You will see that most of the time the entire pack has a chance to be the outright winner the first few laps. By that I mean they will only be about 5-20 meters back of the leader. Then in the last half of the race things will stretch out. I always felt that in the 2 mile, the race started after the first 3 laps. The same is probably true of the mile but it only starts after about 1.5 laps. In other words the early going is not that crucial. You want to run even pace. Most people in high school will have splits like this 70, 75, 76, 73. In the 2 mile it might be 2:17-2:22-2:25-2:20. That is a discouraging way to run, especially if you fall back during the second or third lap!
There are not many books about race strategy. It's because it's difficult to spell out for each person.
Try starting out in last place in practice...Try starting out alarmingly fast....Try starting out in the middle....
Take some of my suggestions but it will be a situation of self-discovery.