How to view user created table in OracleDB?
Is there any other command to view just the tables that I created?

If you know the table name just add it in a WHERE clause:
SELECT table_name
     FROM user_tables
     where upper(table_name) = 'MY_NEW_TABLE'
     ORDER BY table_name;

Or perhaps something like this:
select owner,
       object_name
from dba_objects
where object_type = 'TABLE'
  and created_date &gt; trunc(to_date('05-15-2021','dd-mm-yyyy'))
  order by owner,
           object_name;


Also can someone also explain me, what these tablespace are while
executing the following command


SYSTEM is where the data dictionary lives.  Don't touch it. Don't create your own objects in it.
SYSAUX is an auxiliary to SYSTEM.  Treat it the same.
UNDOTBS1 is where oracle writes 'undo' information - information needed to rollback a transaction.  Not only used for actual rollback, but when a query needs a transactionally-consistent view of the data.
TEMP is the 'temp' tablespace.  Used when operations like sorting cannot be completed in memory.  Kind of like Oracle's version of the OS's page file.
USERS - created by oracle by default to be the default tablespace assigned to users.

More information can be found in the Database Concepts manual.
-Expanding original answer to address additional questions:

So where my user created tables are stored, I mean in which
tablespace?

If you did not specify the TS when you created the table, it will be in the default TS for the user that created it.   You can check this with
select username,
       default_tablespace
from dba_users
order by username
;

To check specifically for which TS a table is in:
select owner,
       table_name,
       tablespace_name
from dba_tables
order by owner,
         table_name
;


What if there are 100 of user created tables, how do I view in that
case of course I can't filter by table name in that case

Then remove the WHERE clause, and (if using sqlplus) spool the output to a text file, which you then open with a text editor:
spool myfile.txt
select .....
spool off