I would say the distinction is between “perfectable” versus “inherently flawed,” but “good” and “bad” works as a simplification.
Systems like our gov’t with its competing branches and factions was designed to spread out and limit power exactly because the Founder understood man to be flawed, corruptible.
Leftist political thought is all about how changing man’s circumstances can bring about a brand new man. That if we just arrange our language and social order exactly the way the anointed architects prescribe, that we can achieve utopia on earth.
Republicans want to take the country to Hell 3 MPH slower than the Democrats.