Beaches are like the smallest and most boring biomes. Other than the turtles, they're totally useless.
1. Palm Trees. It would be cool to have some kind of trees on the beach. It's a tan colored wood.
2. Washed up coral and seashells - Exactly what it sounds like.
3. Tide Pools - Contain seagrass, small fish, and maybe sea stars.
4. Beach Huts - Found randomly on the beach. Made of palm wood planks, stripped palm wood, and covered with vines. One or two villagers live here.
5. Seagulls - Annoying birds that are neutral. If you hit one, a whole bunch will swarm around you. They swoop down to the ocean to catch fish. They can also eat baby turtles that are "running" to the ocean. It sounds sad, but this happens in real life.
Not sure I like the villagers, even though it'd make all the sense in the world. Villages are already fairly common and igloos are only slightly less common (of those, the ones that spawn with a basement are fairly uncommon but not really rare). If villages were made slightly rarer to make room for more-isolated appearances of villagers I'd be fine with this.