If you've spent time reading the CrossFit HQ website, you would have seen videos and photos of the CrossFit 'super stars' demonstrating incredible feats of strength, speed and fitness. Some of you might be discouraged by this, but it is important to focus on your OWN feats.
One of the main concepts behind CrossFit is "scalability" -- meaning the workouts are written for the elite athlete, but you can scale them to fit your needs. Not only is that not "wrong" to do, but it's important for your growth as an athlete. You have to start somewhere right?! Scaling means you can adjust the weight, the number of rounds, the number of repetitions of each exercise, or even the exercise itself. Box jumps might become step ups. Pullups might become band pullups or jumping pullups.
Ultimately the most important ingredient for progress is the amount of effort you put into a workout. No matter how much weight you are lifting and the modifications used, if you give 100% you will experience great results and in time you too will be a CrossFit superstar!