When you are a child you learn about the building blocks of math,science, reading, exactra,
When you are young it is KEY to develop the fundamentals you need to do those subjects more complex
A person who didn't learn addition at age 5 cannot do more complex math when they are older
Understanding the basics of subjects makes the learning that happens later, like in a job or colloge easier
To be a doctor you have to study science, for a engineer its math, so early learning helps in jobs as well
Hope this helps!!