Private key space is 2^256 but address space is only 2^160, so there are effectively 2^160 possible addresses. When you're creating a new address, what you're essentially doing is generating a random number between 1 and 2^160 (1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976). Due to how large this space is, it is all but impossible for the same number to be generated twice. Oversimplified of course, but that's the gist of it.
Thank you for sharing your insight.