The first game my kid played was also at 4, and it was super Mario Odyssey with the assist turn on, which paints an arrow to where to go plus health restores after not getting hit for like 10 seconds. We also got our other kid Bluey because she loves Bluey, and it was super simple to play, but sometimes hard to grasp what they should be doing. I also agree with Kirby, it was basically the 2nd game he played and ended up beating it which was pretty shocking.