Custom datapack for a server im hosting where one of the members has severe arachnophobia but didn't want to use mods. THIS PACK WILL NOT REMOVE SPIDERS, all it does is make zombies drop spider loot. To remove spiders completely from a server and keep most functionality, you'll probably want to combine this pack with:

https://dev.bukkit.org/projects/mobsmanager - make sure you edit the config.yml in your plugins folder correctly for both spiders and cave spiders - once you've editted it should work but you may have to run the ingame command as they still spawned after editing the config

OPTIONALLY: https://www.curseforge.com/minecraft/customization/derecs-wool-to-string - to allow you to craft string.

Mods that achieve similar functionality for single player - I haven't tested these personally but we did explore them as options.

https://beta.curseforge.com/minecraft/mc-mods/arachnophobia - Completely removes them and restores most functionality

https://beta.curseforge.com/minecraft/texture-packs/arachnophobia - Requires optifine, try optifabric if you're using fabric

Also as part of the pack, I included a similar swap for phantom loot and creepers, this is disabled by default to reenable it open the zip, then click data and then through all the folders until you get to the folder containing zombie.json and creeper.disabled - rename creeper.disabled to creeper.json

Zombies drop Spider loot