Back in those days there weren’t labels put on children that set them aside from others which today seem to be the root of much of the bullying today. The slow learners were just that for whatever reason, in many cases all they needed was a pair of spectacles or a home situation where they could do homework properly.
I haven’t moved far in my life so I still see regularly a good many school mates, some at the top end made a lot of money, (millions), the middle ranking ones that got apprentiships in trades are house owners, at the lower end the ability to turn up on time and concentrate through the day has been the key.
The one condition that has caused most problems is attention deficit, dyslexics have done quite well, most have good verbal and practical skills.