It wasn't all that long ago that when someone did something really silly you would say, "use your brains!" to indicate they need to think more carefully before repeating that again.
But what if you no longer had to use your brains? Because now your smart phone IS your brains? What would that do to us as a society? How or why would you have to learn, when you wouldn't need to use your brains?
When babies are first born they have literally billions of neurons, or brain cells. Unlike other cells in your body they aren't replaced through your life. You have them, and if they're not used the brain decides to prune them out. The nerve pathways that would develop to and from them just never develop.
The crucial time for this development is during the first two years. That's why pediatricians beg you not to let your little one be exposed to media technology before then, and after then, only in a very minimal way.
I know, I know, technology keeps them quiet. But think about it, are little babies and toddlers meant to be quiet? No, they naturally explore as much as they can. They touch everything they can find. They're noisy as they go through their milestones of development.
You don't need anything to amuse them, except maybe a piece of paper, or a little piece of string. They'll do wonderful things with simple objects. But don't expose them to your cellphone, or other techie media before they're old enough. Let those little brains develop as they have before smart phones were ever invented. When they explore, using their hands, with different objects a magical thing happens. Those neural pathways develop like crazy!