I think it’s not clear that the causation flowed that way. I think it’s at least partially true that the Republican base was much more isolationist and protectionist than its “establishment” elite, so any significant candidate that played into that was going to get some level of support.

That, combined with Donald Trump’s massive pre-existing celebrity, talent for showmanship, and utter shamelessness got him across the line.

I think it’s fair to say that at least partially, Trump didn’t shift the base - rather he revealed that the base wasn’t where the establishment thought it was.