Yes, we all agree to be Canadians, but we also agree that to be "Canadian" involves many cultures, not one culture.

We don't "all agree to be Canadians." There is a powerful separtist force in Quebec that has been working to take Quebec out of Canada for many years. The separatist party has formed the Quebec government for the majority of the past 30 years and the majority of the Quebec seats in the Canadian Parliament are currently held by separatists.

Furthermore, the Quebec Government specifically rejects the concept of Canadian multiculturalism in favor of an official policy that all other cultural communities are secondary to the francophone majority.