Is my course relevant or not??
There are many different factors that are observed in determining the validity of the course that one chooses to study in Canada. E.g. Your previous education if any, you stated that you're in the Arts area which is fine but at what level? i.e. Secondary, Tertiary etc.
If you have a Masters and apply to do a 2-year diploma then... expect a rejection. You must demonstrate in your choice, a course that will enhance or compliment in some way, your current educational background.
This is just one of many factors that the visa officer will consider as aforementioned. Their decision is based subjectively on the supporting documents you provide in your application BUT objectively, they will analyse and deduce based on their own reasoning when looking at your case in totality. They are trained also to rely on instinct which sometimes isn't the best route, for applicants anyway.
Best of Luck!