Little Fuzzy: Terro-Human Future History Novel, Paperback/H. Beam Piper

Jack Holloway lives a solitary life in a wilderness of planet Zarathustra, itself "owned" by the Chartered Zarathustra Company, which installed basic services and colonial outposts initially, and now reaps the benefits of new discoveries, such as the valuable 'sunstones' mined by Holloway until he befriends a tiny, golden-furred humanoid that he names 'Little Fuzzy.' Little Fuzzy brings his family/tribe to meet Holloway and the lot of them promptly adopt Holloway as well. Upon discovery that the Fuzzies intelligence may qualify them as a sapient species, the Company moves against them.