Strapi’s Admin package and users-permissions plugin are two different things. Created_by is a feature used only by the Admin package for Permissions. If you overwrite it with the user from user-permissions, you can lose access to your own Admin data. Because user from user-permissions doesn’t exist in Admin users and they are not related to each other. Please do not mix them. That’s a bad practice.
To obtain creator, author features with the user-permissions plugin, take a look at the documentation, there you have an example of how to achieve this feature in a few seconds (if you type fast):