***>>>"(Ontology is) what actually exists... Hence, metaphysics literally means what is actually happening in the background of physics." It seems you're trying to avoid the concept of something beyond physics, so I'm hopeful you do understand where I'm trying to go here. Indeed, because your wording seems to have been quite carefully chosen, I think you might realize that agreeing to the largely accepted understanding of metaphysics -- the assumption that physics is based upon something deeper than itself -- would be quite detrimental to your position.***
I'm not following you here. Metaphysics is an attempt to understand the underlying processes of the Universe that are not empirically at hand. All theories are dependent on metaphysical concepts since all theories are not 100% dependent on empirical confirmation. There always exist a future empirical finding that could blow away the results of a good theory. In addition, there are usually elements of a theory that cannot be empirically verified but must be inferred based on the success of a theory. This summarizes a great deal of the antirealist position. Should we treat theoretical unobservables as real (e.g., quarks)? We can avoid the metaphysics by denying the existence of quarks (since we cannot directly observe them), however we are not out of the water. As I mentioned already, particle accelerators are dependent on particle theory being mostly correct. A great deal of particle theory relies on theoretical unobservables (hence an element of metaphysics).
***In my view, we learn to break things down a long time after we start experiencing the world. As such, this tenet of metaphysics seems so certain and unquestionable because we've basically been holists for our entire lives once we finally begin to sit back and bounce our observations off one another.***
By saying that we break things down a longtime after we start experiencing the world, you are much closer to understanding my position. The 'prior experience' is a conceptual scheme that we use to interpret our sense impressions of the world. Each conceptual scheme is dependent on many factors (genetic disposition, evolutionary factors, childhood experiences, etc). We cannot seriously take any particular conceptual scheme as 'correct' or de facto (e.g., a materialist view) since the conceptual scheme we use is horribly tainted from all of these many factors that contribute to that conceptual scheme. This ontology must be studied using the only means by which we can effectively study an ontology, and this is through a serious philosophical inquiry that involves logic, science, metaphysics, etc. That's why, when we study our ontology, there has to be an emphasis on meaning since this is how we attach ourselves to the world. Seeking as much meaning as possible and being as intellectual honest as possible are both required.
***You have said my position is that "meaning" is imputed into reality; I think that this assessment of my position is based within the assumption that if "meaning" only exists within our imaginations, then it is "imaginary." A big part of our problem is is our shared (and confused) lexicon. In my opinion, an "imaginary" object is just as real as a "more-than-imaginary" object.***
So, what keeps the dragon in your garage from eating you right now?
Warm regards, Harv