The roles are slightly different from what we are used to in regular Zoom meetings. In Webinar we have panelists and the participants become audience.
The audience can largely do nothing but listen and ask questions via Q&A - they do not have access to a camera and microphone and thus cannot accidentally click the wrong button.

Host
When you create a webinar you get the role Host.
As a host, in addition to controlling the webinar, you can also make changes to the settings.

Alternative host
When creating a webinar, you can add alternate hosts. It is also possible to add afterwards.
Alternate hosts have the same control as a host in the webinar but cannot change the settings.

Panelist
A panelist can use camera, microphone and screen sharing.
You add panelists by inviting them in advance or changing their role during ongoing webinar.

Invite in advance:
Create your webinar and save.
Go to the Invitations tab
Click Edit and add the panelist's name and email address. If there are many panelists to be invited, you can import them from CSV.

Invite during ongoing webinar:
Click Participants
Click on ... after the participant's name
Select Promote to Panelist, the panelist have to accept the promotion.