I would say it is not difficult to develop a course. It can be a lot of work to develop an exemplary course, partly because of the lesson design work, partly because of the time getting everything developed. But just making a course is like anything else...a learnable skill. If you have the ability to create content in your course, then you already have the ability to experience the basics of Canvas course design. IMHO, this seems like a strange reason to avoid making new courses and could be coming from someone who does not have experience with Canvas.
Now, that being said. It is possible they are saying it is difficult to build a course to THEIR specifications. But that could be mitigated by providing you with the guidelines they expect. An avenue to broach might be suggesting that you would like to learn the process and that this would mean another person capable of helping develop courses. Having more people learn how to create the course would reduce the workload on others who develop courses.
Going with what @dbrace and @JeffTurin mentioned, you might be able to create your own course or ask them to give you want to experiment in. For the former, go to your Dashboard. Do you see an option on the far right that says Start a New Course? If you do, then use that option to create a course to experiment. Or ask if they can create an empty shell because you would like to try and learn more about Canvas without impacting students. I have some videos here that are meant for basic course design. Always intended to do more but nobody has developed the ability to freeze time yet. Lots of other resources out there to help as well.
