From my experience, when an elderly person dies, unless there is some specific reason, authorities rarely look beyond death due to natural causes. Coming from someone who works in facilities where body bags are a regular occurrence, it would not surprise me if many covid deaths were missed along the way. That, and we now know that covid was in North America long before the masses were being informed, and we also now know that some deaths that early on were not attributed to covid, have now been proven to have been exactly that. So dates and timelines are constantly getting moved back. I suspect that a LOT got missed along the way.
I don't believe that anyone feels that covid was already widely around in November or December of last year. If it was, the places where I work would have been wiped out, even worse than they are now. It may have been present on NA soil, that I do believe, but most likely in very small isolated pockets. My wife is convinced I had it back in mid-late December 2019, so waiting to see what possible antibody test says, if I am able to get one. Then again, nothing saying that I would still have active antibodies, several months later - but here's to hoping!
See previous posts regarding your theory.
Where I work the term "outbreak" is common place, we have seasonal influenza outbreaks, along with norovirus outbreaks. But last fall/winter was no different than any other, across the board. I work in several different senior health care facilities on a regular basis, located in different towns & cities. I am also part of a provincial organization, which covers many other cities, including one that has been the hardest hit since covid landed here in my province. Last fall/winter the overall number of deaths from the "flu", were typical, nothing out of the norm. I suspect that you will find the same across most parts of North America.
Where I work, the residents are undeniably the most vulnerable group of people on the planet. In my country I believe the last number I read was 84% of the covid related deaths, were in the buildings where I work, nursing homes, care facilities for the elderly.
So if your theory was correct, across NA, these senior care facilities would have seen a DRASTIC jump in numbers of illness & death, last fall/winter. Yet they did not. In fact for our buildings, we had far less deaths in the fall/winter of 2019/2020, than the previous year.