You hit it on the head. The Shelby name has a legacy but man, it has been taken into the realms of folklore.
The current Shelby offerings (not the Ford manufactured stuff) are created with a mix of parts from great suppliers that are actually "private label" or rebranded. This is good when the supplier has an actual engineering process that includes validation. Some of the the stuff is from an "engineered to fit" mindset (read: worse than the oem parts they replace).
The Ford engineered Shelby vehicles are great. Unfortunately, there is this myth that Shelby helped designed and engineer them. Truth be told, other than some opinion sharing, he just took a big check. I'm ok with that.
There are car people and Shelby people. Car people understand the "big check" comment, no big deal. Shelby people think and perpetuate a lot of lies and myths.
I used to own a 2007 GT500 several years back. There were countless times when I would be at a gas station and get approached by a "Shelby" guy who was clearly a fan of the car and the brand. Usually they would walk around the car and tell me all of the great things Carol Shelby did to help engineer and guide Ford. It would be different stories every time, but each time, all of it was BS. I'm not one to crush dreams so I would just thank them and move along with my day.