Rugo is a quadruped with a big scaly head so he sounds like a Wodenite in Anderson's Technic Civilization History or like similar "xenosophonts" in other science fiction (sf) works by Anderson. Reading this story so far, we are not yet sure that it is sf although that would be a reasonable guess. Rugo's mother would have come to grief when she "...met the Strangers..." (p. 2)
We learn that the Strangers are in possession of the land, also that Rugo has hands and a tail and is old. One Stranger is referred to as "...a man..." so it is a safe bet that they are human beings. Indeed, the following paragraph refers to "...men from Earth itself..." (p. 4) The next revelations are that Rugo's people had been hunted with vehicles and weapons, that the Strangers had been the hunters and that Rugo is now reduced to begging from them.
It took human beings forty years to reach Tau Ceti and colonize New Terra. The natives agreed that they could stay but then opposed them. Possibly, the native counselors had thought that they were agreeing to more explorers, not to settlers. The natives were "...huge and scaled and black..." (p. 6) but the colonists had guns, bombs and a plague virus. Thus, Rugo is the last surviving native.
A good touch is that:
"None of the beasts from Earth could stand the sight and smell of him; they knew he was not of their world and a primitive terror rose in them." (p. 8)
Rugo is driven back into the wilderness by a rifle-wielding farmer and stoned by children led by the farmer's son but befriended by an educated tramp and two children. However, he drowns saving the farmer's son. Sinking, "[h]e wondered if his mother would come for him." (p. 28) This is possible because, when he was old, "...she often came back at night." (p. 2)
Since the entire story until his dying thought has been narrated from Rugo's point of view, the text could have ended with: "He wondered if his mother would come for him." (p. 28)
However, there is one more paragraph, showing New Terra at last without even one surviving Gunnur:
"A few miles further down, the river flows broad and quiet between gentle hills. Trees grow there, and the last sunlight streams through their leaves to glisten on the surface. This is down in the valley, where the homes of man are built." (p. 28)
Maybe Rugo's body goes where the river flows? Quiet river and gentle hills symbolize the end of conflict. The last sunlight symbolizes the end of Rugo's life and race. The narrative ends with "...the homes of man..." because this is now a human world. The title had told us that Rugo's quest would end in death.