When you're building a skyscraper, you are not going to design every brick.
The basis of teaching children how to code is making them learn how to use code as a problem-solving tool. Like this, the sorting will not be important by itself, but as means to an end. As a way to achieve greater objectives.
And besides this reasoning, we have another: in CS, something is generally built on top of others. If you write a heapsort algorithm in C, you don't need to understand it's implementation in assembly. When I write my HTTP Applications I don't need to understand all the Network Layers beneath it. As I write this, I don't really understand the intricacies of Google Chrome and MacOS that make it possible. Am I ignorant? No. There is much thinking and learning to high level coding too. It's all about how complex your problem is and how you learn to apply logic to solve it.