How a Copy of a list works?

Craig created a copy of the list to avoid mutating the list and presenting different output every time the function is called :

def display_wishlist(display_name, wishes):
    items = wishes.copy()
    print(display_name + ":")
    suggested_gift = items.pop(0)
    print("====>",suggested_gift,"<====")
    for item in items:
        print("* "+ item)
    print()

Now, what i do not get is shouldn't the copy of the list stored in 'item' behave in the same way and display the same problem. So if you pop(0) from 'items', it will mutate and have on less items, so when the function is called twice the result is different every time. I thought that copies of lists do not mutate so i tried the following in the Shell:

created a list: list_1 = [1,2,3,4] copied it : list_2 = list_1.copy() then performed pop() on the copy: list_2.pop() then printed list_2: print(list_2): it was one item less [1,2,3] So, How come it didn't change and when Craig used it?