> Magna Carta, which was about the relationship between a king and his own feudal lords.
Among other things. Some important bits applied more widely, such as the right to a fair trial which applied to any "free man".
It was a also a recognition of existing law that had developed earlier.
> Even with that caveat, didn't that really only happen after the medieval era?
No, slavery declined in medieval times, and was abolished in England by the Normans around the 11th/12th century. Serfdom continued but serfs were not chattel slaves (they could not be traded) and has rights.
European participation in the slave trade revived in early modern times, in and between colonies. Slaver was not revived in Europe itself.
Among other things. Some important bits applied more widely, such as the right to a fair trial which applied to any "free man".
It was a also a recognition of existing law that had developed earlier.
> Even with that caveat, didn't that really only happen after the medieval era?
No, slavery declined in medieval times, and was abolished in England by the Normans around the 11th/12th century. Serfdom continued but serfs were not chattel slaves (they could not be traded) and has rights.
European participation in the slave trade revived in early modern times, in and between colonies. Slaver was not revived in Europe itself.