Victor Stenger observes that the teleological explanation “makes the wholly unwarranted assumption that only one type of life is possible”. (p. 89)
That is not a necessary conclusion of the teleological explanation for God’s existence. There might be other types of life forms (such as silicone based). That would still not explain the incredible odds that the universe exists the way it does such that humans could live. Even if there were countless types of life forms, the universe would still be tuned in such a way that humans could exist. Even if humans were just part of an ensemble, the question of why we are here would still remain. There is no naturalistic reason why the universe should be tuned that way. Given how incredible those odds are, a non-naturalistic explanation needs to be sought. The fact that we appear to be the only life forms makes the argument even stronger.