I'll just offer this observation:
The reason folks are even bringing up standard musical notation as a response to your question(s) is because otherwise you'll be reinventing the wheel.
There already exists a solution to the problems you describe, and it's a solution that has evolved, developed, been vetted, tested, and codified over hundreds of years. It has a vastly comprehensive vocabulary that has nearly universally agreed-upon meanings, and it transcends most differences in upbringing, culture, preferences, and ideologies.
Arguably learning to use standard musical notation would not take longer than some hypothetical solution that avoids having to embrace that pedagogy; rather, it's a shortcut versus having to invent a new solution from square one.
It's one thing, when someone while they have access to free public education, or even electives in private education gets these concepts drilled into their head, much like learning to read and write starting from kindergarten, using tried and tested practice regimen designed to help turn that language into something natural to them over the course of years. Even more incentive that you are being graded in your ability to perform such a task.
It's another when those opportunities are long gone and you've made do with what you've had over a course of decades which amounts to simply having a instrument in your hands and learning via a process of elimination, plus a few short lessons in theory amounting to having some knowledge of scales, intervals.'
You can preach all you want, that I should learn how to or be able to do something you can.. however not all circumstances are the same.
My circumstances, as well as MANY musicians I've met over the years, provides that we play music without such tools and being older, I'm not any better at learning new languages than I was while I was in highschool.. and barely learned/remember a lick of two semesters of Spanish, as I've never had cause to use it daily and in practice. I lived in Germany for three years, but can only say "Good day", "Egg", "yes", "no," "please" "thank you" or I can count to 10, maybe even twenty. Perhaps a few other select words.
For whatever reason, pursuing a self education in the written language of music doesn't work for me.
But I'm glad this thread has turned into a debate about whether or not I should learn to read/write rather than creative suggestions about how to help build someone's sense of rhythm without being able to do so.
You guys have fun with this thread.. to which half the responses don't seem to understand the reasoning of the original post.
Best wishes through the madness the world's going through.. I hope it's a big enough eye opener to the majority of the human species to embrace people, and their differences, rather than bicker about what one thinks is right.
There are probably a high number of players out there who get by without such a skill. Some of them probably pretty successful at it. Seems those people aren't the ones chiming in on the thread though.
I'm not here to debate this. Thanks everyone for their suggestions. But I'm unwatching the thread at this point. I'm done trying to explain myself and MY circumstances, which differ from many of your own. There is a phrase for understanding there is more than one single solution to a problem, it's called thinking outside of the box.
I won't post threads like this in the future. I'll just figure it out myself. Has been working for me thus far for my needs and tastes.