I encourage you to get to know very well this discomfort and fear you're experiencing. It's part of the process of being a traceur, and one of the biggest benefits of being one is the chance to frequently confront situations that instruct us about exactly who we are. It's only natural to compare yourself to those around you, I know I have. However, what's important isn't what you notice in those comparisons, but how you respond to what you find.
If you see that they can jump farther or higher, or are more fearless, what's a better response:
1) Deciding you want to improve yourself and finding the best specific information on how to do that. Setting a goal, doing research, training hard and measuring yourself against yourself.
2) Getting discouraged and quitting because you're not good enough.
3) Deciding that you're not going to let fear rule you and going out constantly and trying to match or beat them, often attempting things beyond your abilities.
There are of course many other paths before you than these three. I hope you find one that will help you learn as much about yourself as possible while improving as a traceur in a safe manner.
I've faced essentially the same situation. My progress has been much slower than the people I started with. I don't have the genetic leaping ability of one of my friends, or the years of gymnastics of another. What I do have is the willingness to work my ass off, and the support of this amazing community. Nothing else has ever mattered to me in the same way parkour has, probably because nothing else has allowed me to so consistently face myself in healthy and positive ways. haloshade2, I hope you find the journey as rewarding as I have.
P.S. Read the stickies in the General Fitness Forum
, get access to a gym and start lifting. For me lifting is just as satisfying a spiritual and mental journey as parkour.