A team, named All members, includes everyone in your organization. People who join your organization following an invite link are added to All members, with the role you choose, via the invite link. Permissions granted in All members apply to all spaces by default.
For example, if Lisa is an admin in the All members team, she will be admin by default for all teams created. You would need to specify/change her role for the created team if you want her to have different permission.