Data File Creation Date
To check the creation date time of data files, we should query V$DATAFILE, not DBA_DATA_FILES.
First of all, we format the date time of current session.
SQL> set linesize 200;
SQL> column name format a60;
SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
Session altered.
Then we perform a query on V$DATAFILE.
SQL> select name, creation_time from v$datafile order by 1;
NAME CREATION_TIME
------------------------------------------------------------ -------------------
/u01/app/oracle/oradata/ORCL/example01.dbf 2020-07-20 23:25:31
/u01/app/oracle/oradata/ORCL/sysaux01.dbf 2020-07-14 23:22:46
/u01/app/oracle/oradata/ORCL/system01.dbf 2020-07-14 23:22:46
...
For a multitenant container database (CDB), you should additionally check the container id.
SQL> column con_id format 9;
SQL> select con_id, name, creation_time from v$datafile order by 1,2;
CON_ID NAME CREATION_TIME
------ ------------------------------------------------------------ -------------------
1 /u01/app/oracle/oradata/ORCLCDB/sysaux01.dbf 2019-04-17 00:56:21
1 /u01/app/oracle/oradata/ORCLCDB/system01.dbf 2019-04-17 00:56:09
1 /u01/app/oracle/oradata/ORCLCDB/undotbs01.dbf 2019-04-17 02:11:02
...
As we can see, every data file has its own creation time, we can use the information to determine the creation date of a tablespace.