This is a simple and lightweight plugin that utilizes one of the many Paper only API additions.
Just drop this jar into your plugins folder and restart your server and then phantoms will no longer spawn because of you while you are in creative mode. This does not interfere with spawning from other players like other Spigot plugin equivalents do, even if those players are near you.
No config. No Permissions. No commands. It just works. \o/
Source Code: https://github.com/BillyGalbreath/NoCreativePhantoms