The Sirens don't attack ships directly. They simply sing — and their song is so irresistible that sailors steer straight onto the rocks trying to reach it, wrecking themselves on shores littered with the bones of everyone who came before.
Warned in advance by Circe, Odysseus knows exactly what waits ahead: creatures whose song draws sailors so completely that they forget to steer, wrecking their ships on the surrounding rocks. What makes the Sirens' song genuinely dangerous, according to the text itself, isn't simple beauty — they claim to know everything that happened at Troy, and everything that ever happens across the fertile earth. The temptation is total knowledge, not merely pleasure.
The only mortal to hear it and live: the plan works exactly as designed. Odysseus hears the Sirens' full song, strains desperately against his ropes, begs to be released — and his deafened crew simply rows on, carrying him safely past. He becomes, within the mythic tradition, the one mortal known to have heard the Sirens' complete song and survived to describe the experience.