Having been around during 9/11, Reagan was a bigger inflection point. He was directly responsible for ramping up the arming of the groups that would go on to form al Qaeda. But, that's a small contribution compared to overseeing the decoupling of productivity from pay and his war on labor.
Just because it's not the underlying cancer, a tumor will still kill you. Had he croaked earlier, he might have caused a lot less damage to the US and by extension the world that it's not given premature Bush Sr would.
Reagan was shot only about a year into his 8 years in office. If he was taken out then and Bush Sr stepped up, then the total reign of that awful administration would have been many, many years less. Plus Bush didn't even come close to having the same pull as Reagan. Reagan was charismatic. He was a POS, but he knew how to talk to people and get them to agree with him - he was an actor for Pete's sake, so he had all the "soft skills" to connect with both Republicans and Democrats. Bush Sr was nothing like that. He was just another "generic" politician who couldn't even get reelected.
Our country would be vastly different today if JH Jr was a better shot.