Of course your Constitution was written for an 18th century society.
Human nature makes up society. It makes people who they are and that does change over time. you can't suggest that the mindset of people today, reflects that of someone in the 1700's. I know what you are trying to suggest, natural instinct etc. but natural instincts DO change, look at animals for instance. Natural instinct of a dog is to bite, however over many decades, many breeds have been pacified so it is inherent in their nature NOT to be aggressive toward humans, too many generations pass and their history becomes their nature.
Certainly core human value such as protecting family, home, finding food, etc. are natural instincts, but that is merely a survival 'instinct', not to be confused with human nature, which does change over time as needed.
To suggest otherwise is to completely discount evolution, every life form on Earth evolves as needed as does their mental nature.
Man has evolved a lot over time, even though not so much physically, certainly what is deemed human nature has also. Even then, man has physically evolved over time too, even in the last few hundred years.
Evolution changes everything, physically and mentally.
To suggest that human nature was understood so well, in the late 1700's, that they were able to draft a short set of rights that would suitably carry Americans into the next millennium is pretty naive, especially for you.
In the late 1700's they were only just getting over having legal witch hunts! Great grasp of mankind indeed!
"We've found a witch, may we burn her?"
"How do you know she is a witch?"
"She looks like one"
"Bring her forward"
"I'm NOT a witch, I'm NOT a witch!"
"But you are dressed as one!"
"THEY dressed me up like this"
"Did YOU dress her up like this?"
"Noo, noo, well a bit, a bit, we did do the nose,...and the hat, she's got a wart!"
"How do you KNOW she is a witch?"
"Well she turned me into a NEWT!!!.......uh, well it got better, but she's still a witch!"
