Mario Odyssey has an easy mode for young ones. Mario Kart has a mode to make racing easier also and is great fun, my youngest also loves Kirby. Splatoon 2 is one of our faves. I love zelda but it would be too difficult for a 5yo. Quick post as I'm busy but anything you want to know just ask as I'm Nintendo mad
Yonder the cloud catcher chronicles is very much like a simplified more cartoony version of Zelda. There's no combat, an open world to explore, animals to make friends with and little sprite things to find and other quests to do from NPCs. My six year old niece loves it and can play it on her own with occasional help to read instructions etc. Also I would second Mario Kart.