Why is belonging important but not the most important thing in life?
You can say that a belonging could be important as a material thing but more important if it holds greater values like a memory, sentimental meanings, spiritual/religious meanings, or unique ideas/information. Just like how art paintings go worthily. Just a piece of cloth/canvass and color paintings, but the beauty and message it conveys to the beholder makes it more important than the other. Also, you can use the obvious concept that material things are not forever thus less important than a memory or important information/feelings/life.