One thing about old games (pre n64), is that you don’t have to worry about controlling the camera. Younger kids like 5 or so have a hard time enough time timing button presses so making them also have to figure out how to control the camera/is very frustrating for them. Isometric, top down, and point and clicks work best for younger kids.

I also think the super Nintendo controller is the best for children and people with small hands. 8bitdo makes a good modern one with more buttons and triggers so you can play modern games.