"The way Trump basically came out of nowhere to totally re-define the GOP (and simultaneously sideline titanic GOP figures like the ones you listed, plus Romney) within the space of a single term is unprecedented and remarkable"
He didn't redefine them, they redefined him.
You don't know how politics works, do you? No one votes for something, they vote AGAINST what the 'other' brings.
Hatred is the great unifier. That "If it weren't for the Jews, I would have had to invented them" line that Hitler may or may not have said? The bigger the aspirations of the depot, the greater the demonization of this year's featured creature must be.
Now lest anyone start crying "Why you call him Hitler?" I ain't. At least not just him. They all are, in a sense, just occupying different spots on the scale. Some are Hitler, some are Carter. Most are inbetween.
Look up the origin of "Build the wall." Wasn't Trump. That rallying cry was given to him, because his message needed a way to spike the ball. At times of economic malaise, them Wetbacks become our Jews for the latest pogram.
As for redefining, you're paying too much attention to the optics. They're using him, son - Republicans and Democrats and their Oligarch backers. The hell y'all think Pelosi DID NOT WANT TO IMPEACH HIM, then screwed it up royally when she had no choice, ya stupid jackoffs?
He's that stupid rich kid in hs that the jocks became 'friends' with when rich daddy bought him that Maserati. Friday night, we're headed to Joey the Retard's house to party because he folks are cruising off on their yacht round the Keys for the weekend.
Trump is the Golden Goose. Their fall guy. Their fool.
Tell the trailer park boys that they'll be gettin their valuable fruit pickin jobs back because we're gettin rid of the Mexers. Tell the bottom lickers by making the richer way richer, Walmart will give them a whole $500 bonus for Christmas. Maybe. Tell the pro-lifers that Roe v Wade is going away, and they can hump their cuzins in peace knowing darkie won't be killin all them unwanted babies. Tell them that the Redeemer hath cometh from the depths of Sodom, and he's gonna blast them cityfolk back to the hell from whence they came. Tell them that the South has risen as He Is Risen, and they will raise their arms for the Rapture.
Populists don't get power by telling people truth, they do it by telling the moronic masses what they want to hear. Children like stories, and what a tale this gilded Messiah weaves.