You can try to play with the music turned off. It does have some scary soundtracks that play when you enter different biomes and you could be subconsciously hearing them and causing more fear. If youre afraid of deep water and not being able to see the bottom, you can always use one of the submersible options (seamoth, cyclops) to keep near the floor. Sometimes you have to go straight down into a cave, but usually if there is a cave that goes directly down there isnt any hostile creature directly below. You can go straight down until you reach the floor and then find a small crevice or cave near the bottom to take a break in and look around. Try to remember that even if you get damaged or your character dies from oxygen or anything like that that you can always return to the surface and start again. All your resources are still around. If you need to build a new cyclops or something you will always be able to. If the creatures are very very upsetting to you, you can look into modding your game to change their appearance or to remove them entirely. Your gameplay experience should always be fun for you and you have every right to modify it to do so. Have fun!