When combined, 日 (sun) + 本 (origin) create 日本 (Rìběn), the name for Japan—the “origin of the sun”. Adding 人 (rén) simply specifies you are talking about a person from that country.
While “日本人” is a neutral descriptor in daily life, its usage can be colored by the deep and often difficult history between China and Japan, particularly the events of the 20th century. In most contexts—discussing a tourist, a colleague, a celebrity, or Japanese culture—the term is completely neutral. However, in discussions about history, politics, or in nationalistic online forums, the same word can carry a heavy weight and may be delivered with a negative tone. A helpful comparison for Western learners is the term “German” in English. On its own, it's a simple nationality. But when discussing World War II, the word, while unchanged, is heard within a specific, somber historical context. Similarly, the neutrality of “日本人” depends heavily on the context of the conversation. For learners, the key is to always use the term in a neutral, respectful manner, as it is intended in normal, friendly communication.