What are these generic looking activities from sp_who2?
All of that appears to be the result of normal Sql Agent activity.

Assuming you don't have any 'real (non-system)' Sql Agent job running (meaning you don't really need the Sql Agent running), my suggestion would be to create a Windows Task scheduler process using SQLCMD to run your sp_who2 process on your defined interval and then STOP the Sql Agent.  What gets logged into your table then?