[nephihaha]

Beowulf has a Scandinavian background to the story. Shortly after "hwæt", it mentions "gar-Denas" or spear Danes. (Old English had become heavily influenced by Norse by the time of the Norman invasions, especially in ita northern dialects.)

There may be a Celtic influence upon it as well, as with some of the Icelandic sagas, but you would have to dig much deeper for that.

[antonvs]

The language and style of Beowulf is Old English, though. Old English was a West Germanic language, already closely related to the North Germanic Old Norse and mutually intelligible to a high degree.

But it doesn't make sense to say "such interjections were unlikely to be used by speakers of Nordic languages in order to begin a tale" without some sort of explanation for the focus on "Nordic" languages. Subsequent comments have made it clear that the commenter is under the mistaken impression that Old English was a Nordic language. It was not.

[spyrja]

Actually, the introduction of Old Norse in Britain began in the early 5th century and by the time of Beowulf, Old English was still more than 90% a Nordic language. The Norman invasion of 1066 changed that dramatically (as Old French became the "new" official language) and to this day Modern English could reasonably be considered mostly French, then Latin, and only in small part Nordic (although the most common words used are by majority derived from Old Norse counterparts.) Oddly enough, only a few Celtic words made it into the language.

[nephihaha]

Germanic and Celtic languages have been in contact for at least two thousand years. Probably longer. There are Celtic loanwords in English which predate the Anglo-Saxon invasions. After the invasion, English took centuries to expand into areas which spoke P Celtic, and it seems to have profound influences on its verbal structure. Another wave of Celtic loanwords entered English via French.

As for modern English, there are numerous Celtic loanwords and calques in American, Canadian and Australian slang and dialect.

[antonvs]

Old English is not considered to have evolved from a Nordic language.

Old Norse was a North Germanic language. Old English was a West Germanic language. They were mutually intelligible to a significant degree, since both were Germanic languages that evolved from the hypothetical common ancestor Proto-Germanic, but saying Old English was "90% a Nordic language" is like saying that humans are 90% chimpanzees. Both evolved from a common ancestor, one did not evolve from the other.