Because Beowulf was written and set so long ago, it addresses some interesting topics. One of these is that it reveals to us some of the changing attitudes as Europe was becoming Christian. We can see elements of both pagan and Christian attitudes in the epic.
Beowulf is one of the earliest pieces of printed literature. However, when you say it was written in the 1600s, you are wrong. Beowulf was written about 700 a.d. , and it was set about 500 a.d.
Beowulf was probably written down 800 years or more earlier than you have indicated. The basic plot of this epic poem involves the efforts of the hero, Beowulf, to defeat three different monsters: Grendel, Grendel's mother, and a dragon. Beowulf fights the first two monsters when he is a young man; he fights the third when he is an old man and a king.