How to view the latest entries in all tables in an Oracle DB?
You can identify most recently created users/schemas from dba_users view

select *
from dba_users
order by created desc;


When you know what schemas to look out for, you can list the most recently created tables with

select *
from dba_objects
where owner in ('SCHEMA1','SCHEMA2')
  and object_type = 'TABLE'
order by created desc;


For a single table, you can find a rough date when the data was last modified

select scn_to_timestamp(max(ora_rowscn)) 
from schema.table;


Or get a list of rows that were (potentially) modified last

select *
from schema.table
where ora_rowscn = (
  select max(ora_rowscn)
  from schema.table
);


Note that ora_rowscn is stored by default per database block, not per row. There is a limit how old scn values can be mapped back to timestamp.

You should also check the audit trail

select * 
from dba_audit_trail
order by timestamp desc;