إذ لو كان جائز الوجود لكان من جملة العالم
For if He were contingent in existence, He would be included within the world.
In this discussion “the world” denotes the totality of created or contingent realities other than Allah. If what is proposed as the ultimate originator of the whole is itself just one of those dependent realities, the explanation has not reached a being beyond that collection.
This does not deny ordinary intermediary causes. Fire's involvement in heating is not the same claim as being the independent ground of every dependent thing. The latter requires freedom from dependence.