"NT" isn't some kind of profound statement about diversity; it's just a way to refer to someone without a neurological condition without saying "normal". At this point, "normal" has too many connotations about it (the idea that normal is good and abnormal is bad, chiefly), and it's better to use a term like "neurotypical" which is a great deal more factual. Professionals sometimes use the term "typically developing," which means the same thing but refers only to children.
In any event, "typical" is not the same thing as "identical". Neurotypicals are in the average range; they are not all the same, and it would be silly to assume they are. They're simply not far enough off the cognitive norm for it to be a striking quality about them.
There are a great many other things to a person than just neurology. Their personality, their sense of ethics and compassion, their decisions, their interests, their environment... Neurology and genetics don't predetermine who a person will be. Neurotypicals may not have unusual neurology, but they can be, and often are, unusual in other ways.
Your estimate of "95%" is probably off by a good deal, incidentally. We have approximately 1% autistic, 3-5% ADHD, 1-2% mentally ret*d, 1% epilepsy... that's more than 5% atypical already and we haven't even gotten into learning disabilities, sensory integration, or motor coordination... Then there's the acquired stuff, like TBIs, post-stroke, Alzheimer's... You want to get into the motor regions of the brain, and you can add cerebral palsy and developmental dyspraxia... The figure for people without a diagnosable neurological condition is probably a good deal smaller than 95%.