The way it is supposed to work is this. It is the same me typing the reply up to the point of change. Right now I choose to delete this reply or continue. I choose continue, so there is a bifurcation point. The theory holds that there is another universe now where the message was deleted and not sent. The me in that universe is not aware of me and vice versa. There will be totally different versions of me based on the changed experiences, like the one that didn't ditch the girl and am now divorced with three kids to support and no time to play with toy soldiers
That is how the theory is generally accepted however, the point I’m arguing is that the people who made those decisions are not, have not, and never will be you. They are not other me’s, they are other persons. Because you are exacted of a very peculiar and immutable set of experiences any modification to them even in the most infinitesimally small manner changes you to someone else because YOU did not experience them. That point aside and as yourself stated each variable person does not share consciousness and there is no democracy in the selection of one over another, each exists (if even another does exist) as a separate entity and their paths do not intercept. In truth the suggestion that there might be an election of such nature implies a higher power which unfortunately cannot be proven or disproven with any certainty.
The issue of math being the universe I struggle to come to terms with. It means the language is the reality (not necessarily in a dualistic sense)
It is a bit like the Christian Logos and the divine fiat. I find that a difficult concept to deal with.
I don’t think scripture has anything to do with reality. The way I look at the bible and things religious is that they’re very simply guides by which to live your life by. Take the Ten Commandments, by themselves they are excellent rules to live by and in truth the beatitudes are very beautiful as is the book of Job but they’re not grounded in reality. Their parables and like all other parables the truth of them does not lie in the facts but the meaning. That said I’m not sure math is dually reality. When you put an equation to paper the material equivalent does not (at least to human knowledge) somewhere else appear. We have to apply the equation to the real world. What math is, is a language that describes the force which governs the universe, it is not the force which governs.
Think about Shakespeare, he says: What is a name? That which we call a rose would by any other name smell just as sweet.
In the same way math is only giving a name to the force (and maybe force is a little too supernatural a word but I’m lacking for another) which governs the universe. Even without a name it exists, and exists even if no one knows about it. It’s a constant I suppose though it is said that before the birth of the universe strange things happened, who can know what?
Intent and meaning are not separate, at least according to Merriam-Webster, they are synonymous:
Main Entry: 1in•tent Pronunciation Guide
Pronunciation: n. tent
Function: noun
Inflected Form(s): -s
Etymology: alteration (influenced by Latin in- 2in-) of Middle English entent, entente; Middle English entent, from Old French, from Late Latin intentus aim, purpose, intent, from Latin, act of stretching out, from intentus, past participle of intendere to stretch out, intend; Middle English entente, from Old French, from Latin intentus (past participle) -- more at INTEND
1 a (1) : the act, fact, or an instance of intending : PURPOSE, DESIGN <suspect him of hostile intent -- S.M.Crothers> <came with intent to kill> (2) : the design or purpose to commit any wrongful or criminal act that is the natural and probable consequence of other voluntary acts or conduct (3) : the state of mind or mental attitude with which an act is done : VOLITION b : an end or object proposed : AIM <used his leisure time to good intent>
2 a : MEANING, PURPORT, IMPORT, SIGNIFICANCE <paraphrase in speech the intent of the communication -- Edward Sapir>; specifically : INTENDMENT 2b b : the connotation of a term
And even though you may have neglected the meaning of your statement a meaning is still carried over and interpreted whether you intended to send it or not. Body language is good example of this. When you’re angry your brows may furrow unconsciously and this sends a meaning regardless of your intent. For this reason I’d say that you’re partially incorrect when you say that there is no exact interpretation of meaning. I know what it means and you know what it means and really from a human perspective it can mean nothing else. It’s a universal expression amongst the species. Can it be faked yes, can it not be recognized? Hard to believe but I’d say yes. So only partially incorrect

. Now, going out of body language into linguistics, we can go back to what Confucius said, when you’re specifc and accurate in what you want to say it will not be misinterpreted. You have to factor of course that the person receiving your comments is equally capable of understanding but I don’t think that’s ever out of the question.
Now for the last bit. Math is objective aye, but I don’t believe that it’s necessary for physics or for anything else. I’ll go back to what I said earlier, math is just a description and whether or not it exists in our minds doesn’t influence one bit the force that governs. A different example, the wind blows, if you take its name air is still being pushed around by inequalities in the atmospheric pressure. Take away anyone and anything who could give a name to it and who could perceive it, it still exists. Because it is not dependent on us or our language. Remember mathematics is a language developed by humans, it is not supernatural.
Language does presume communication it also presumes beings capable of communicating. Does it imply a being that’s intelligent, that depends on what you mean

do you mean like dolphins or dogs or creatures who have achieved self-awareness?
And again don't worry if I'm a philosopher I'm only an amateur, God forbid a real one weigh in