But the duckling having been a misplaced swan all along means the message isn't...
Be kind to others, because everyone deserves respect regardless of their looks or abilities
Be kind to others, in case they turn out to be posh, pretty or powerful
What if the ugly duckling had just grown up into an ugly duck? One of those hybrid things perhaps, that are part Mallard, part Muscovy, and all wrong? Would picking on it have been totally OK then, because it didn't grow up to be anything special?
Of course not: every creature deserves kindness, regardless of how pretty it is.
But there's this lingering idea that if you have a disability or illness or difference, you have to be extraordinary in some way to 'earn' your humanity. You need some metaphorical swan's feathers to offset the inconvenience of your presence or the cost of your care. For Aspies, it might be the assumption that we all have savant skills or academic brilliance to make up for our sensory or social struggles. Bipolar-type conditions seem to come with expectation of creativity or genius or both, and some people talk up schizophrenia as a spiritual experience.
Some people on the spectrum do have amazing abilities, conferred either by their neurology or through hard work and dedication. And some of us don't. Some of us are just chilling in the middle of the bell curve. We're doing our best, but our best just happens to be unremarkable, ordinary and average. Just like most other people's best.
And that's OK. Because everyone matters, and everyone deserves respect and kindness. Even the ones who don't grow up to be swans, or have a fairy godmother to shower them with nice stuff, or turn out to be a long-lost member of the royal family.
Even those of us who are just ugly ducks.