When I was in Highschool we learned a lot about Dieppe and while some of it might be wishful thinking on our part as Canadians some of it was proven I’ll stick with the proven stuff.
-Dieppe as many know was used as a trial as nobody had ever done any large scale landings before and there were a lot of unknowns at the time. This included time it took to get to shore, how to get vehicles and equipment ashore under fire, would air superiority be a factor, how large of a naval force and supply chain was required and several other factors. We also know the hard lessons that were learned at Dieppe and were used for the planning of the invasion of North Africa.
-this was also an intelligence gathering mission as the Canadians were to storm the German areas command offices and get as much intelligence as possible and were to capture any Germans especially officers for intel gathering.
-this was also to be used as a morale booster not only for the civilians, but the government and military as while there had been successes in the Mediterranean it was far from home. While we now know what happened during that time both the press and government communiques spun it as positive raid although it was a military disaster.
-*** this one is up for debate as I learned this in school and could be wrong. As to why Canadians were used instead of Battle tested British troops supposedly the Canadian government and military pushed both the British military and government to lead this raid as both a morale booster for Canadians and because Canadian soldiers had been languishing in Britain for almost 3 years at this point with nothing to do but train and be bored.