Well the hashes are always much smaller than the actual data, otherwise downloading the hashes would take just as long as downloading the data lol.

So 16KB blocks means 131072 bits per block, subtract the 256 bit hash size and that means 2^130816 hash collisions

That's a lot lol, you'll never find which one is the correct one. Even if you instantly had a list of all values that match the desired hash, you'd have to check them all and somehow determine which one was correct.