"the existence of a thing does not prove that it could have come into existence in any different way"
If you accept laws of physics and don't ascribe any metaphysical properties to the thing - then yes it does. It might be unlikely, but you can just put the atoms in a proper configuration and you will have your thing.
Putting atoms into their proper configuration takes other atoms in their proper configuration, and there's no reason to assume that there is more then one such proper configuration.
"the existence of a thing does not prove that it could have come into existence in any different way"
If you accept laws of physics and don't ascribe any metaphysical properties to the thing - then yes it does. It might be unlikely, but you can just put the atoms in a proper configuration and you will have your thing.
Putting atoms into their proper configuration takes other atoms in their proper configuration, and there's no reason to assume that there is more then one such proper configuration.
There is actually (because of symmetries in laws of physics).