Answer:
I'm pretty sure the problem is that you're prompting the user to input a string value instead of an int value. This can be done by putting int() before input()
To clean it up your way, try doing:
my_lista = []
n = int(input())
my_lista.append(n)
n1 = int(input())
my_lista.append(n1)
n2 = int(input())
my_lista.append(n2)
min_num = min(my_lista)
print(min_num)
If you want to shorten the code, you can also do it this way which gives you the same output:
my_list = []
for i in range(3):
n = int(input())
my_list.append(n)
print(min(my_list))