Why Did Beowulf Not Live In Britain

As we all know, Beowulf, who came from the Geats, traveled to the Danes to help the king Hrothgar to kill the monsters who often attacked people of the Geats. However, for the epic poem, some questions occur to me, which likes “why does the hero Beowulf not live in Britain? Even, why this story has no concern with Britain?” or “why was Beowulf, as a pagan story, preserved and circulated by the Christianity in the Dark Middle Age?” and so on. Consequently, after I finished my reading about Beowulf and others books about its reviews, and my thinking about above questions, I got the answers to the questions roughly.
Firstly, it is said that Beowulf was recorded through writing down by a Christian poet in the beginning of the Middle Age. Simultaneously,
One was that the fight between Beowulf and monsters, Grendel and his mother, demonstrated the thought of the struggle between good and evil in Christianity. That’s because Grendel was the offspring of Gain, who was the eldest son of Adam and Eve. It is known that Gain was the evil person due to his killing his brother. Of this, the victory of Beowulf embodied that evil wasn’t able to defeat good in Christian spirits. Next, the dragon, which hurt Beowulf heavily and made him died ultimately, represented the arch devil Satan. It was a regulation in the allegory of the church. The consequence of the war between Beowulf and the dragon manifested God defeat Satan finally, and gave the world peace and life. The second one was that the spirit Beowulf held was similar to the Messianic spirit in Christianity. It meant that there always was the savior to save the whole people in the world. Beowulf overcame a lot of troubles and resolved many problems to accomplish his slaying the monsters and the dragon alone, so that he saved thousands of lives in the Danes. The final one was that Beowulf was from the Geats, which was a distant place for the Danes, crossing the borders, wading through water, and climbing the mountains to get to the Danes. In here, Beowulf took place his great achievements in his life, inheriting the throne of the Danes King, ruling the country with the rest of his life; and, finally, he died in the Danes. In