Teaching a class likely meant to inflate the GPA of student athletes
You wondered "how high does this go?" At my university, the football coach's salary is 7 times the president's. Who do you think answers to whom? The chancellor, the president, the provost, the dean and your chair could all agree with you and nothing would be done. (And if they were the sort of people who agreed with you, then they would not be the chair, dean, provost, president, or chancellor.)
You're new and adjunct, and so have a very weak position. I'm pretty sure this is why you were assigned the course. Options:
Refuse to teach the course and hope that the there's enough bad publicity when you are fired, that the school quietly removes the course. You'll be unemployed, but will have done a service.
Teach the course in such a way that the students actually have to work and learn things. Milk the "participation" for all it's worth. If you do it right, you'll never get the course again. (E.g. Lead a discussion each meeting on the topic of "Why major in STEM." Point out that the very course they're in is robbing them of their opportunity to get a real education. They're essentially slave labor for the billionaires who really own the athletic teams. They're playing pro-football for free and getting in return a worthless degree in "Undergraduate Studies" which won't qualify them to sell used cars. Wouldn't a STEM degree be more valuable and satisfying? That's on-topic for the course and should prevent you from having to teach it again. OR perhaps, choose a nice, science-y book and require that "participation" means taking turns reading aloud from the book. When this uncovers that half your students can't read....)
One possible option is to prepare a syllabus for the course which adds some legitimate graded work: homework, an exam, a paper or project, anything. Then, email it to your chair, mention that you want to evaluate the students' mastery of the material and hence devised your own grading rubric, and ask for her approval.
If she approves, or if she switches your teaching assignment, then problem solved. And if she says "please use the syllabus I gave you", then you have established a paper trail.
Finally, keep the following in mind: in my discipline, I've seen advanced graduate courses where the grading rubric is openly "everyone gets an A". The rationale is that graduate students have more important fish to fry, and should be able to set their own priorities. Whether athletes should be able to do the same is debatable -- but keeping this in mind might mitigate your distaste, if you end up having to use the syllabus you were given.
I'd bet pounds to pesos that this course is akin to the Geology 101 course my brother took (at a major football university) with most of the football team (he wasn't a student athlete, just took the course) that was commonly referred to as "Rocks for Jocks".
However, that doesn't mean (as Buffy mentioned) that the course can't benefit the students. If I were in your shoes, and I would try to make the course give some benefit to the students. If you are allowed to change the syllabus to include some assignments (be they tests, homework, or projects) that get graded and give the students feedback, the students could actually learn something. When I was teaching (at the high school level), I taught a "Descriptive-level" Chemistry course; the basic concept was Chemistry without math. My goal was to help the students learn concepts that would help them (e.g. why you need special coating on screws used in pressure-treated lumber.)
OTOH, this worries me:
...I have now discovered that there is not only one version of this class, but three (XXXX 3910 Explorations I, XXXX 3920 Explorations II, XXXX 3930 Explorations III) versions of the class.
The classes meet concurrently in "different" rooms, however it is really just one big room that can be subdivided into three classrooms with accordion curtains. (Each section of the room has a separate door to the hallway and a separate room number). So the "Explorations" classes can effectively be taken all at once by signing up for all three classes and then just sitting in the big room and "participating."
If this is true (a student can take three courses at the same time and earn credit for them), that would constitute fraud (at least in my book). Given your non-tenured position, I leave it to you to determine if burning the bridge to this opportunity is worth it to you to report the fraud. (I suspect that, should you report, your position with the university will be terminated, or made very uncomfortable.)
Lastly, the attendance policy is something I would examine in greater detail. If your school is as sport-centric as you fear, I wonder if the athletes are considered exempt from attendance (or automatically get credit), should they be on the road. (I.e. if they get automatic points for attendance when they are away, it is another very damning piece of evidence that this is a fraudulent class.)