If you're not familiar, you might like reading about the social model of disability: https://en.wikipedia.org/wiki/Social_model_of_disability

TL;DR: Disability is not inherent in difference, but rather a combination of the difference and an environment in which that difference is not well-supported. For an analogy - a deep-sea fish is blind, but not disabled by their blindness. Similarly, a kid who "can't sit still" isn't disabled unless we put them in an environment where they have to.