My son Milo, who will be 5 in May, has been playing Minecraft on a PC since about the time he turned 4. He started with just exploring a new world in creative mode, and I would build some things for him to use. I built a spawner that produced passive creepers that he enjoyed shooting with a bow and arrow.
But things really turned a corner when I downloaded the world from Minecraft U's creative server and let him play that map. Suddenly the potential of the game was revealed to him, and he explored the map excitedly and thoroughly.
Finally, when both he and his 7-year-old sister wanted to play together, I let him get on the creative server itself. With admonishments to not break any blocks, his joy was multiplied to be able to play together with his sister on the same map. And his skills increased rapidly. I noticed his precision improved. He built some things modeled after other builds on the server. He could navigate different areas more easily.
This past weekend they asked to be put into survival mode. He's not ready to fight zombies, creepers, and skeletons yet, but he's ready to make his own way without an infinite supply of blocks in his inventory. He's got the bug. 😂
By the way, if you have young children playing Minecraft on the PC, I recommend getting a portable laptop mouse for them. It fits their hands much better than a standard-sized mouse. We have two Logitech M187 mice for this purpose.