What is my sin, and why did God not make me brave and courageous, fearing no one but Him? And why did He make me a coward, even though I am always obedient to Him, pious, and dutiful to my parents?

Allah has divided provisions and morals among people with justice and wisdom. Therefore, one should not question why a person did not obtain something, for what Allah gives is purely by His grace, and what He withholds is due to His justice and wisdom. Acquiring courage is possible, and the pious are more deserving of it. One should trust in Allah, train oneself to be bold, and frequently recite the reported supplication for seeking refuge from cowardice.