Trump is the Republican Party.
The Republican establishment abandoned conservative principles during Bush '43. They expanded Big Government, started an undeclared war of foreign adventure in Iraq, and socialized private sector financial losses and malfeasence.
Mitt Romney ran against his own Masachusetts healthcare plan.
John McCain flip-flopped on illegal immigration.
John Bohner, Paul Ryan, Kevin McCarthy, and Mitch McConnell were underperforming and underwhelming Congressional leaders.
The GOP needs better talent, better coaches, and a new owner after Trump bankrupts it.
The worst part is, the party has such good and effective leadership at the state level. Yet get to the feds, and it turns to garbage.
There is such a potential for solid conservative governance from the Republican Party, and every opportunity there is to bring that to a national level, it gets squandered. Be it in the House, or the Senate, or Presidential primaries. All those names you listed... of all the guys on that list, the only one who was reliably conservative was Ryan, but he wasn't a leader.
The Republicans have become a bizarre coalition of old-guard upper-class politicians (Mitch, Romney), the Trump cult, and a small minority of conservatives like DeSantis. That's up against a Dem coalition of the woke, and the remnants of the old political machines in the northeast.
We will get nowhere in this country so long as conservatives only make up 10-15% of the voting population at most, and declining.