This is a linkpost for https://atheistkit.wordpress.com/ethics/
It is not a clear expression of something that can be seen to work
Version 1.
I am obligated to both do and not do any number of acts by any number of shouldness-equations
If that is the case, anything resembling objectivism is out of the window. If I am obligate to do X, and I do X, then my action is right. If I am obligated not do to X, and I do X, my action is wrong. if I am both obligated and not obligated to do X, then my action is somehow both right and wrong..that is, it has no definite moral status.
But that's not quite what you were saying.
Version 2.
There are lots of different kinds of morality, but I am only obligated by human morality.
That would work, but it's not what you mean. You are explicitly embracing...
Version 3.
There are lots of different kinds of morality, but I am only motivated by human morality
There's only one word of difference between that and version 2, which is the substitution of "motivated" for "obligated". As we saw under version 1, it's the existence of multiple conflicting obligations which stymies ethical objectivism. And motivation can't fix that problem, because it is a different thing to obligation. In fact it is orthogonal, because:
You can be motivated to do what you are not obligated to do. You can be obligated to d what your are not motivated to do. Or both. Or neither.
Because of that, version 3 implies version 1, and has the same problem.
If you are interested, I might recommend trying to write up what you think this idea is, and see if you find any holes in your understanding that way. I'm not sure how to make it any clearer right now, but, for what it's worth, you have my word that you have not understood the idea.
We are not disagreeing about something we both understand; you are disagreeing with a series of ideas you think I hold, and I am trying to explain the original idea in a way that you find understandable and, apparently, not yet succeeding.