A Shahed is only useful against stationary soft targets, which an aircraft carrier is not. It also doesn’t have the kind of heavy warhead or terminal guidance required to defeat the armored structure of naval ships. Shahed doesn’t have any kind of countermeasure avoidance. Adding these would massively increase the cost.

Naval anti-ship drones have been around for many decades. This is a highly evolved area of military technology with a long history of real-world engagements upon which to base design choices.

The standard naval anti-ship drones are Harpoon, Exocet, and similar. These are qualitatively more capable than a Shahed and you still need a swarm of them to get through.