PhD definitely has its ups and downs. And when the lows come it can be normal to feel useless or even lose hope. The experience can be amplified if you don't have a good sense of direction right now. But doing a PhD is like holding down any job: the first 2 years you constantly put yourself in new situations, handling new problems, interacting and getting used to new personalities, dealing with new politics. Over time you will figure out how to survive, how best to interact with difficult situations and people, how to solve academically challenging problems that seemed insurmountable at the beginning. You will grow as a person and reach a point when most tasks become old hats. Then you will graduate!