Is there any evidence that manifest destiny was a widely and deeply held conviction amongst common Americans? I'm not asking to be contrarian – I really have no clue.
It seems more believable that it would only be deeply held (if held at all) by the westward bound.
The USA was not originally created with the notion of "manifest destiny"; that was a concept of the 1800s, not the 1700s when the United States of a America was born. Wikipedia reports that "Newspaper editor John O'Sullivan coined the term manifest destiny in 1845 to describe the essence of this mindset" https://en.wikipedia.org/wiki/Manifest_destiny
"The Citizens of America, placed in the most evitable conditions, as the Sole Lords and Proprietors of a vast tract of Continent,comprehending all the various Soils and climates of the World, and abounding with all the necessaries and conveniences of life, are now by the late satisfactory pacification, acknowledge to be possessed of absolute freedom and Independancy. They are, from this period, to be considered as Actors on a most conspicuous Theatre, which seems to be peculiarly designed by Providence for the display of human greatness and felicity" -- George Washington, shortly after the Treaty of Paris (1783)
Even if manifest destiny was not primary in the hearts and minds of a majority of colonial American citizens, their most potent leader saw it as the common bond that would unite the colonies.
Sure, there is a ton of US history to support it. Seemingly every historical book on the subject lays out the premise that it was a very widely held cultural belief (but not universally agreed to). I've read three books on the subject, and they all agree that it was a common populist belief. In fact, it was still a commonly held belief right up until essentially the cultural shift of the 1960s and 1970s.
It seems more believable that it would only be deeply held (if held at all) by the westward bound.