It is true that the only One we can depend on is Allah. However, sometimes Allah sends us those who will help us in our times of need.
For example, if we are not well, we will go and visit a doctor to help treat us and get better. But we will still pray to Allah for a cure. The cure comes from Allah but we still need the doctor to treat us.
Allah tells us to be kind to each other and to be there for each other. We need each other. We need to look after each other whilst we are here on Earth.