Are there any roads (or ferry service) that would allow a person to travel from Canada to Greenland without taking a plane?
There are no ferry connections between Greenland and Iceland, Denmark or Canada. However, more and more cruise shipping companies are choosing to include Greenland on their itineraries, whereby it is possible to begin the voyage from Iceland or go onboard at, for example, Kangerlussuaq.
Greenland being an island, I hope it is obvious that there are no roads linking it to a continent. While theoretically the sea freezes, the ice is not traversable by anyone other than a well-prepared team equipped for arctic exploration.