I feel like this is an extremely unpopular opinion but I really don't think republicanism was a step forward for humanity.
Monarchy is the most intuitive form of government. People tend to take care of what they own, and politicians have no incentive to leave anything better for the next generation because they really have no stake in their country. Their legacy dies with them.
A monarchy with constitutional (and familial) checks and balances is vastly preferable to a republic where the foreign interests run free and loot the taxpayers. It's pure and much simpler. No Congress, no Supreme Court, no ridiculous sham elections. Everyone knows who's in charge and what the rules are.
It is simply possible that government is impossible to get right.
Anything and any ideology can work for a time -- yes, including communism -- but something, somewhere will always start to fail. It's just about the amount of time it takes to fail that sets some (communism, socialism) apart.
The Founders could have written more strong words that were more protective and specific and it would have stopped these issues.
It also would have helped if we had more commonly available works from the Founders to smack down the notion of modern "interpretation" of the Constitution.
Ours may not be perfect, but I think where it is failing is not the type of government itself.
I mean types of governments are not perfect and all have strengths and weaknesses. Even monarchies are not perfect and will eventually succumb to corruption. Venice itself would become corrupt with the black nobility. But that is because the common people become irredeemable corrupt. However, in America that has happened much faster because there are no bulwarks like the Church, or the Christian King to nip such revolutions in the bud.