why the parent task and dynamic task is not the same?
I'll like that when adding a child task the system will set the parent task as a dynamic task automatically.

If it is a parent task, without being marked as dynamic, the percentage of completion, and hours will not be auto calculated based on the child tasks.

If it is a parent task, without being marked as dynamic, the percentage of completion, and hours will not be auto calculated based on the child tasks.
What's the function of a parent task without being marked as dynamic? I think that a dynamic task is in common use.

We use Parent tasks as a grouping mechanism a lot.

We may or may not then have dynamic tasks under those Parents - but there's a perfectly reasonable need for Parents that are not necessarily updated by their children.