Excluding Book children from a Custom view
This can be done with Normal filter in views.

Following is the configuration of the filter UI, You need to separate the both content type in the filter with OR and in the Content Type: Book page you need to Book: Depth = 1. 



Now in the following image you can see the Article and Book page titles, First one without Book: Depth =1, Second one with Book: Depth =1.

 

Hence, You can see the views fetches the all articles and only parents books page.