What has tended to happen when populations have interacted whose languages have been mutually unintelligible is that they eventually create what's called a pidgin language. Basically members of each group will learn a few words in the other s'mores language, and create a simplified mutual language from those. From there, new generations of children are brought up from each group, and these children grow up hearing the pidgin language being spoken. These children incorporate what they hear as part of their native language, eventually culminating in a fully formed language which is a mixture of two older languages, that is, a creole language.