toArray() call, add
$result = Number::limit('1000')->get(['number'])->pluck('number')->toArray();
That's it! This will pluck just the
number attributes from your result collection, and give you a single-level array.
The reason this works, is because you are getting a Collection back from
All multi-result sets returned by Eloquent are an instance of the Illuminate\Database\Eloquent\Collection object, including results retrieved via the get method or accessed via a relationship.