Does it matter if the very first user, usually Admin, does not have a user ID of 1?

No.

If the plugin relied on it, it was badly written – if I found such a plugin, I would delete it instantly because you can’t know which other mistakes the authors made.

Actually, plugins shouldn’t care about the ID at all, but about the user’s roles and capabilities. In the end, IDs are only needed because it makes it easier for the database.

Related Posts:

  1. Is there a simple way to manage capabilities per user?
  2. Can I create users that have access to *some* other users posts instead of all other users posts?
  3. Set default page for user account in admin
  4. Managing Users and Creating Groups [closed]
  5. Are User Levels Still Currently Used?
  6. Fix permissions for users role
  7. How do I let contributors edit their posts after being approved once?
  8. Groups and subgroups for permission
  9. User Permissions on custom post type
  10. WordPress install checking permissions of user id 0
  11. current_user_can() returning true for capability when the user and role do not have the capability
  12. If the current user is an administrator or editor
  13. Editor can create any new user except administrator
  14. Find out if logged in user is not subscriber
  15. Groups of capabilities: users with multiple roles?
  16. User-edit role setting distinct from wp_capabilities? [closed]
  17. Execute a function when admin changes the user role
  18. Disallowing Users of a Custom Role from Deleting or Adding Administrators?
  19. What the user_status column?
  20. Add Custom User Capabilities Before or After the Custom User Role has Been Added?
  21. Hide Admin Menu for Specific User ID who has administrator Role
  22. Grouping users under parent user
  23. How to update user role without logout
  24. Do not allow users to create new posts and pages
  25. How to enable the theme editor cap for an editor role?
  26. WordPress keeps asking for connection information in localhost
  27. How to assign an additional/extra/second user-role to multiple users (of a specific user-role)
  28. How to stop a user from updating the post date
  29. WordPress edit_user_profile_update update secondary role
  30. How do I properly format the user_role array?
  31. Reapproval for edits and deletion after post is published
  32. Admins can’t edit each other’s posts
  33. How to customize wp_signon()
  34. Is it possible to get a user with just the password field?
  35. How to get the Role Name of the current user? (WordPress)
  36. Redirect after login based on user role (custom login page)
  37. set_role has no effect
  38. Users roles, make a page belonging to multiple users
  39. Tagging users in WordPress
  40. Redirect after users complete profile form
  41. How do I list in the backend all users that were assigned to a custom role?
  42. How to add local users to wordpress without email password?
  43. Getting users by specific capability, not role
  44. add_cap not working with Shop Manager role
  45. How do I customize the dashboard?
  46. How to disable a specific page for a specific user
  47. Error: How to allow the “contributor” to upload media in wordpress
  48. Roles for Custom Post Types
  49. Remove Capabilities from WP admin for specific user role
  50. wordpress user roles are not working
  51. Displaying different in-page content to cliente/admin
  52. User capability for editing their own comments
  53. What are some best practices for user exit strategy?
  54. Is there a way to identify a user in a custom REST API method? [duplicate]
  55. How to force authors to ‘submit for review’?
  56. Problem with automatic role change through cron job
  57. Allow Contributors to Upload Files
  58. Is possible to allow user to login with different role?
  59. custom user role wordpress – grant guest access to edit.php without insert/update/delete
  60. Add a role and give admin priviledges
  61. How can I prevent certain custom roles from seeing other custom roles on the user list page?
  62. Restrict access to non-wordpress section of site with user roles?
  63. Load user by specific role
  64. What’s the correct way to add capabilites to user roles?
  65. Fix ‘Add Role’ Option not there in wordpress 5.2.2
  66. User roles not displaying
  67. Allow admins to login as other users
  68. Preventing role reading others posts
  69. Assigning multiple or additional capabilities to specific users or how to create additional roles like bbpress roles?
  70. Change User Role based on Point System Issue
  71. How do I modify the user role ‘subscriber’ to allow the user to delete posts
  72. Editor role can only create/edit/delete users who have one of two roles
  73. How to make WordPress ‘editor’ role to list/view/add/edit users only with the role ‘author’?
  74. Show posts who published after registration date
  75. How to hide “Change role to” dropdown on Users admin menu
  76. Find count of WordPress users by role and search string for user name
  77. hide page menu from admin panel for specific users
  78. fine-grained capabilities for user related capabilities
  79. Disabling user capability to edit_posts or delete_posts in the front-end
  80. In admin manage users page, how can I stop users with certain privileges from editing users with other privileges?
  81. User Role not showing in Users Screen
  82. Groups roles & capabilities
  83. Custom User Role: Can Edit Own Page, Cannot Create New
  84. Button for users to upgrade their user role + Button to show current user role!
  85. Allowing users to edit only their page and nobody else’s
  86. How to bulk change user role to “No role for this site”
  87. Restrict Access to the User Profile
  88. Subscriber role – blank page
  89. How to get only 1 role from user
  90. Front end login and page restriction
  91. User “none” role
  92. Giving users an editable homepage/business directory
  93. i need to let a user to add a role from a frontend form
  94. Limit user access to installing/configuring a plugin?
  95. Increase by one the user counter on specific role
  96. How to give access to the particular page in wordpress for specific username/email NOT roles [closed]
  97. Redirect user based on role when they try access a particular page
  98. How to create a specific role to manage users
  99. Send email to user if their role is changed to Author
  100. Remove My Account Menu items in Woocommerce based on user roles
error code: 523