you cannot, in good faith, simply argue that "we should do X because it is the moral thing to do"
The lens I would view this through is that the decision to act or not is a moral question. That being said, you're 100% right because through my lens that all actions are moral ones then saying "we should act because its moral" is the same as saying "this is moral because it's moral", circular reasoning and all. I should have been more clear in saying that all my points to my argument (in the OP) were reasons to support the morality of acting in this situation. Good catch though.
If both disagree, and are of similar levels of power, then all actions are immoral, as no actions would be taken
Before addressing this specific point, I think a visual would make it clearer. I think I understand your construct here though so: In this case, what if the inaction would cause harm to one or the other? The system would have to find a way of balancing the wants and needs one the two moral agents with one another.
Overall, if you can draw a "box" around an object, and that actor would result in an action, or would have the mindset required to set that action to occur, then that action can be called "subjectively moral"
Agreed. I said it in passing in one of my earlier comments that if all life were to go extinct, then morality would go with it. So while morality isn't objective in the sense that it's omnipotent, written in the fundamental laws of nature regardless of who's perceiving it, it is "objective" in regards to who it pertains to: humans (you called this subjective morality).
However, I'm not 100% clear on your notions that all actions are subjectively moral because all immoral actions don't occur. What do you mean by that?
It may be useful to get rid of "immoral" as a category entirely, and instead only consider actions to be "moral" or "not moral", or "I would cause this" and "I would not cause this"
Similar to above, what happens when your actions and inaction have consequences? At that point you can't simply abstain from acting since both acting and not acting will cause (let's say) harm to one person in one case and another person in another case.
There is no objective morality based on the definition I give above
I spoke to this above too, but to be clearer here since I don't think I have been completely: I think we're using different definitions of "objective." I don't think there is an objective aim (since we both know of the concept of good and bad are measured against an aim, let's talk about an aim instead of the word "morals"; means to an end, and all that) in that it's written in the stars and will continue to exist outside the scope of humanity. I think the aim is objective in regards to the scope of humanity (drawing the box around humanity, so to speak). But what do I mean by "objective." I mean that there exists an aim that we all aim at by default and without the need for argument for it, or against another. For me, that aim is human well being. In that sense, there exists an objective aim.
While I did read it and have some points on mind, I think the common ground we found is far more interesting to discuss. Besides, the overarching theme was addressed above anyways (objective aim).
I do want to comment on the last part specifically (points 1-5). I would actually like to revise the points to make them clearer and to highlight that these are observations rather than a self containing argument:
1) All humans desire well being as the aim to their actions
2) Actions that increase human well being are good in regards to humans' natural aim (1)
3) There's no compelling argument to change our aim
4) Our aim remains as it is, and the goodness of our actions are measured against it
it assumes that "actions that increase human well being" exist. Due to the first point being false, humans can seek different things for their well-being, and as a result no single category can satisfy this point fully. Actions that increase "human well being" may well not exist.
First, let me give an example of a specific action that will increase well being: Me taking a breath right this very instant. No one suffers, I gain (ever so slightly): well being increases. Second, when you say "no actions exist that can increase well being" I think you're thinking of general actions (e.g. donating to charity), then thinking of an instance where that general action can decrease well being in a given circumstance (e.g. the charity robbed you). But remember that we're dealing with a system that takes these variables into account here. So if you're faced with a dilemma (donate to charity?), you look at the variables (are they going to rob me? No) then you can act knowing (reasonably so) that your action increased well being.