Synonyms:
bungler, blunderer, fumbler, bumbler, stumbler, sad_sack, botcher, butcher, fuckup
Meaning: someone who makes mistakes because of incompetence
Usage examples
For my part, I was always a bungler at all kinds of sport that required either patience or adroitness, and had not angled above half an hour before I had completely "satisfied the sentiment," and convinced myself of the truth of Izaak Walton's opinion, that angling is something like poetry--a man must be born to it.