Does an Oracle user have all privileges in its schema?
SQL Language Reference


  Prerequisites
  
  For you to select data from a table, materialized view, analytic view, or hierarchy, the object must be in your own schema or you must have the READ or SELECT privilege on the table, materialized view, analytic view, or hierarchy.


but


  To issue an Oracle Flashback Query using the flashback_query_clause, you must have the READ or SELECT privilege on the objects in the select list. In addition, either you must have FLASHBACK object privilege on the objects in the select list, or you must have FLASHBACK ANY TABLE system privilege.


So for a simple select it is sufficient to own the objects. But if you want to make a Flashback query on one of your tables, you need additional flashback-related privileges.

Also you have UPDATE, INSERT and DELETE privileges on the tables of your schema.

Details you need to execute a statement you can find in the prerequisite sevtion at the beginning of the chapter that describes a statement in this manual.