How about a proton? It is quite a bit more "complex" than its various component quantum particles, but I assume you would agree that it arises by natural processes without the need for supernatural involvement.
How about a hydrogen atom? It is quite a bit more "complex" than its various component sub-atomic particles, but I assume you would agree that it arises by natural processes without the need for supernatural involvement.
How about a uranium atom? It is quite a bit more "complex" than something as "simple" as a hydrogen atom, but I assume you would agree that it arises by natural processes without the need for supernatural involvement.
Now, if you do in fact agree that the above can arise by natural processes, at what point do you impose a cut-off, beyond which "natural" complexity is impossible?
How do you know that those things weren’t created with those properties that make them behave reliably as they do?