This question is, of course, a very controversial question in Canadian history. The answer depends on one’s own opinion about the nature of heroism and the degree to which Canada’s government was acting justly towards the Metis.
On the one hand, it seems hard to argue that Riel is really a Canadian hero. This is, after all, a man who took up arms against the Canadian government. He is also a man who might have been guided by delusions and driven by mental illness to take the actions that he did. How can we characterize such a man as a hero?
On the other hand, we can argue that the Canadian government’s actions towards the Metis in Manitoba were so wrong-headed that it was necessary and proper to rebel against that government. We can say that Riel was a hero because he was willing to resist the evil actions of the government even though that resistance would eventually get him executed. In this view, we can see him as a hero and a martyr for the idea of rights for all Canadians, regardless of their linguistic or ethnic heritage.
I would tend to argue that Riel is a hero because the Canadian government of the time was not worthy of obedience. A person who stands up against injustice can properly be called a hero.