If you want to get really, really, REALLY technical, then yes. Just like all humans descended from Africa, the First Nations/Aboriginals (difference between Australian Aborigines), immigrated to the Americas from most likely the Bering Strait, a massive landmass that connected eastern Siberia with Alaska. However, the Aboriginals had been the established human presence in the Americas, in this case specifically Canada, for thousands upon thousands of years before any contact with Leif Erikson, much less any post-Columbus explorer five hundred years after the Norseman. So to answer your question, technically the Aboriginal peoples of Canada are immigrants in the lands that they inhabited before anyone else. However, this is in the extreme genealogical definition of immigrant, just in the same sense that anyone reading this (unless your family is Ethiopian or other East African nationality) are an immigrant. Hope that answers the question. Moderators, I hope this answer was satisfactory, and feel free to edit this answer if I missed something.