Ticket Created is not a field in the database.
Nearly all tickets are created by the user that owns the ticket.
If the ticket is create by an Agent, its still create for the user (owner), and it adds a note to the events saying (agent name) opened ticket on behalf of (username).
If someone change the owner of the ticket from one user to another user... it adds a note to the events.
Visually you can see this in the ticket thread.
If you really really really need to know this information then you would need to look at the ticket and each event to see if either event is listed for the thread.
The Database ERD might help you understand this
https://docs.osticket.com/en/latest/_static/images/erd_Tickets.pdf
