Write a function to perform a specific task (e.g., sorting, searching) for a Tech Mahindra coding exercise.
For this exercise, implement ascending sorting for a list of integers using insertion sort. Return a new sorted list and do not modify the input list.
Input: A list of integers.
Output: A new list containing the same integers in non-decreasing order.
Constraints: The list contains 0 to 1,000 integers, and values range from -10^9 to 10^9.
def sort_numbers(nums):