Careful referring to broad variable philosophical concepts like ontology and metaphysics to justify your 'might be unknown,; because these philosophies in some versions do not reject that our physical existence as natural, but speculate on the underlying causes and relationships of our natural existence
For example:
Metaphysics of Science | Internet Encyclopedia of Philosophy.
Metaphysics
simpliciter seeks to answer questions about the existence, nature, and interrelations of different kinds of entities—that is, of existents or things in the broadest sense of the term. It enquires into the fundamental structure of the world. For example, it asks what properties are, how they are connected to the entities which have them, and how the similarity of objects can be explained in terms of their properties. The subject matter of metaphysics is somewhat heterogeneous: topics include the composition of complex entities (such as tables, turtles, and angry mobs), the identity and persistence of objects, problematic kinds of entities (that is, entities about which it is unclear whether or in what sense they exist at all, like numbers and fictional objects such as unicorns), and many more. Metaphysics is usually understood as working at an abstract and general level: it is not concerned with concrete individual things or particular relations but rather with kinds of things and kinds of relations.
Metaphysics of Science is not completely disjoint from metaphysics
simpliciter. Not only does it draw on the pool of methodological tools employed in metaphysics, but there is also substantial overlap regarding subject matter. Metaphysicians have their own reasons, independently of science, to investigate causation, modality, and dispositional properties, for example. Like space and time, these concepts pertain also to everyday phenomena. Although Metaphysics of Science, too, is usually attentive to our everyday intuitions and opinions about such phenomena, it engages in a specific investigation of the roles these concepts play in scientific contexts.
Metaphysicians of science often take scientific realism for granted—that is, they hold the philosophical stance that the sciences are apt to find out what the world is really like, that they track the truth, and that the entities they postulate exist. Antirealism about science, on the other hand, often coincides with a skeptical or agnostic attitude towards metaphysics. In the context of some broader metaphysical inquiries, scientific endeavors might well be seen as but one way to the truth. A mainly science-guided metaphysics might even be seen as mistaken (as, for example, in phenomenological approaches (compare Husserl 1936; 1970)).
Your vague obtuse philosophy is close to what may be called Ontological Idealism.
The world being natural is not a fact. By definition the world being natural is based on objective facts regardless of what may be speculated as the underlying causes or relationships.