Through Hrothgar's achievements the poet suggest his own system of values. What seems to matter most to the people in his society?
The poet doesn't spend a lot of time in Beowulf extolling the virtues of Hrothgar. For most of the story, Hrothgar is therather defeated king of a people plagued by a ravaging monster. In the geneology at the beginning of the work which explains how Hrothgar assumed the throne, we do see what Hrothgar once was--and will presumably become again once Grendel and his mother are dead.
The text I'm using is the Seamus Heaney translation, but the ideas will be similar in all translations, I presume. There are three aspects of life which seem to matter most to the people of the day, as valued by the poet(s) who sang/wrote Beowulf. (This corporate authorship over time adds a complication to your question, which refers to a single poet. The values of every poet who passed on the story as well as the monks who finally transcribed it from an oral story into a written one--as well as the translators, to some degree--are undoubtedly reflected in the finished work, as well. However, we have to deal with one text, so here goes.) We'll presume the poet/storyteller sang/spoke about what mattered to the people for whom he performed.
The first thing we learn is that Hrothgar was an effective leader. We read that "the fortunes of war favored Hrothgar." He was apparently an effective leader in battle.
Friends and kinsmen flocked to his ranks,
young followers, a force that grew
to be a mighty army.
This is evidence that a good leader is one who can win in battle--something which was quite common in that place and time. People were willing to follow someone who could defeat his enemies. Ironically, of course, Hrothgar will later be paralyzed, in a way, by the marauding Grendel. But not so in the beginning.
The next thing Hrothgar did which shows us what the poet, and presumably the people, valued was to build a great hall.
...So his mind turned
to hall-building: he handed down orders
for men to work on a great mead-hall
meant to be a wonder of the world forever.
This great hall served the dual purpose of protection from enemies, as it's the place all would come for shelter from whatever danger was upon them, and a symbol of a town's greatness to the rest of the world. Remember, their world was a much smaller place than anything we might mean by "the world." It was a sign of greatness and power to have a fine, artful, and grand hall in a town. It's the first thing Hrothgar did after returning from his successes in battle, indicating the great value of a great hall. Again, ironically, this hall is virtually emptied by the threatening presence of Grendel.
Finally, Hrothgar was faithful to reward those who deserved it. He "doled out rings/ and torques at the table." This is a picture of a gracious and grateful king. Being recognized and rewarded for services rendered was a value of the poets, and presumably all Anglo-Saxons. This giving of gifts as a reward for services rendered is a foreshadowing of what's to come for Beowulf.