[Python] How does Python insertion sort work?

Here's a Python implementation of insertion sort, I tried to follow the values on paper but once the counting variable i gets bigger than len(s) I don't know what to do, how/why does it still run?

def sort_numbers(s):
for i in range(1, len(s)):
val = s
j = i - 1
while (j >= 0) and (s[j] > val):
s[j+1] = s[j]
j = j - 1
s[j+1] = val

def main():
x = eval(input("Enter numbers to be sorted: "))
x = list(x)
sort_numbers(x)
print(x)

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