Did the damage inflicted at Taranto show that Italy's large battleships were not a serious naval capability?
Short answerNo; Taranto was a difficult, specialized operation, and several damaged battleships were recovered and returned to service.
NotesOperation Judgement was neither easy nor a generic demonstration that any aircraft could neutralize battleships in harbor. British Swordfish used torpedoes adapted for shallow water, including fins and a restraining arrangement that many observers did not appreciate. Several damaged Italian ships were recovered and returned to service. The attack reduced Italian strength without erasing the Regia Marina's balanced fleet.