Thank goodness I did dancing outside of school as other than gymnastics/ aerobics, I was beyond hopeless at traditional athletics/ team sports. I suspect dyspraxia for a multitude of reasons (and DS has a diagnosis too). I have always done something for fitness into adulthood, but it never stemmed from PE.
Generally PE has improved since my days in the 90s of being sidelined and insulted, and it's disappointing that those days aren't totally obselete. My issues were being the smallest by a considerable margin, poor technique, terrible co-ordination and poor equipment. It took my PE teachers 4 years to realise that I genuinely was that shit. I still dutifully turned up with kit and it seemed to finally click that I wasn't trying to duck out of it, but was actually just that inept!
It was mobile phones that taught me how to run after the PE teachers failed to teach any technique, and it's social media that feeds encouragement. It certainly wasn't the PE teacher yelling "come on, you aren't even trying" as I wheezed past, shins on fire and stabbing stitches, or the classmates chanting "lapped you, lapped you twice, lapped you three times" It's bloody lonely and embarrasing being out there alone still doing the 1500m while everyone else is done and has their breath back.
The irony is that running can be great for neurodiverse people as there is little co-ordination involved, and you can get a social and competitive atmosphere at places like parkrun/ races without the obligation and social pressure and closed pool of school, and just have the competition with yourself if that motivates you. Or it can be as casual as you wish.
Last does not mean unfit or lack of trying, and no other subject is taught this way. It's like randomly saying "do long division... you got that wrong, do more long division" with no attempt to explain how to do it.
I'm glad you're looking into this OP.