I completely understand your concerns as I was also intimidated by the curriculum outline for my Chemical Engineering program. However, trust me, you are anything but average. There will always be people who have talents that differ from yours...that doesn't make them smarter or better equipped in pursuing a chemical engineering degree. For me, the greatest difficulty wasn't the perplexing math questions or physical chemistry and thermodynamics problems that I probably still couldn't solve to this day, the greatest difficulty was having the self-confidence to challenge myself to continue. Most students, like you, have worked hard and achieved high academic accolades as reflected in their grades...it's not about grades! You are going to embark on a very challenging academic journey that will challenge you mentally. There will be concepts you will grasp easily and others that you may never understand. As long as you do your best, challenge your mind, and focus on the learning other rather than the grades, and strive to pursue your own standards of achievement (regardless of the grades, behaviors, or specific talents of others that differ from you) you will succeed...I promise!
Don't give up!