Newton wrote down the law of gravitation in 1687. People weren't floating off into space before then. The same thing applies to the NAP. Just because it was called something different doesn't mean it was actually something different.
Look at the history of casus belli. Cato the Elder wanted war against Carthage because they were becoming a threat and should be destroyed while they were weak. The Mongol Khanate wanted war because they were stronger and thus it was their right. Both of those are very much a might makes right casus belli. The Peace of Westphalia brought about the NAP between nations even though it was not called that back then. In fact the entire concept of jus ad bellum is just a variation of the NAP.
Newton wrote down the law of gravitation in 1687. People weren't floating off into space before then. The same thing applies to the NAP. Just because it was called something different doesn't mean it was actually something different.
Look at the history of casus belli. Cato the Elder wanted war against Carthage because they were becoming a threat and should be destroyed while they were weak. The Mongol Khanate wanted war because they were stronger and thus it was their right. Both of those are very much a might makes right casus belli. The Peace of Westphalia brought about the NAP between nations even though it was not called that back then. In fact the entire concept of jus ad bellum is just a variation of the NAP.