Want to know Slack account concepts

Slack can sign in to multiple workspaces with one email address.
You can configure different profiles (passwords, profile images, and display names) for each workspace.

"Also, where can I find ""Account for Slack Service, not for workspaces"" on Slack?"

At first, I thought, "Slack is an account for each workspace and there is no account for the Slack service itself."
↓ It seems that there is no concept of which account to create and register this rack app, so I think there is an account of the Slack service itself.
https://api.slack.com/apps/

The URL of the installed application list page includes the workspace ID, so it seems to be separated by workspace, but the above api page did not separate by workspace.
https://app.slack.com/apps-manage/XXXXXX/integrations/installed

In the administrator confirmation screen for each workspace below, I thought that the workspace that I am the primary owner would be Slack's account.
You can transfer the rights of the primary owner to someone else
I mean, if you have zero workspace in your primary owner, and
You may have more than one workspace of your primary owner, but
I don't know how Slack's account will be handled at that time
https://XXXXXX.slack.com/account/workspace-settings#admins