The Magna Carta was based on remnants of the Roman legal system, surviving in the Latin-literate clerical population of England.
Yes, I know. I was referring to this in your link’s post:
Human rights laws existed before the Magna Carta (Jews followed it in the Torah long before that)
American Thinker ^ | 06/16/2010 | Ethel Fenig
The MC was an elite v. elite document. The hoi polloi weren’t a party to it and it is miraculous how it came to pass as a document of general and not limited rights for all. I suspect the Christian influence via the Torah as the reason.