A creole is usually defined as a specific form of socially-influenced language change, one where a pidgin language was spoken, and it gained sufficiently wide-spread usage to the point that it was acquired as a native language by children. A pidgin language is a simplified communicative system created by two or more adult populations who do not have a language in common. The question, then, is whether a pidgin arose given contact between Saxons and Vikings, or later English speakers and Norman invaders. However, the domain of "creole" is expanded by some linguists (Mufwene for example) to include cases of significant contact induced influence, without the pidginization requirement. So it would really depend on how you define "creole", and how you distinguish it from other forms of contact-induced language change (such as Arabic influence on Spanish, or English influence on Korean). There is no independent metric of whether a language should be called a creole versus something else. Rather than expanding the definition of creole to include all forms of language contact (leaving us with no distinction between cases like Kituba or Haitian versus Korean), we could leave the definition of creole alone, and construct a different terminological category for Louisiana French.
