Chester Gorham Osborne
The First Lake Dwellers
1956
from the dustjacket:

Enemies destroy the lake people's village, steal their stores of grain, and capture Arvi's father, Chief Calling Hawk. Arvi finds a way to build a shelter on his father's fishing raft on the lake. There he and his mother and sister are safe from human enemies and from wild animals too.

When Calling Hawk escapes, he uses Arvi's idea, and he and other villagers build more and more lake dwellings. Hawk tries to persuade all the villagers to join together for the common good, but the hunters refuse. They do not care for the new farming life, but prefer to live by hunting so they can be free to move quickly when danger threatens.

The same fierce enemies attack the lake dwellers again, but the houses on the lake prove to be safe. Enemy arrows cannot reach them.

Then Arvi, the swift-footed, goes to bring back the hunters. Standing together, the united villagers win a great victory and look forward to a new life of peace and co-operation.