In my understand, you can using the RACF SMF data unload utility modules (IRRADU00 and IRRADU86) to extract SMF type 80, 81 and 83.
The output will show who create the userid you want to know.
You can find it by search "ADDUSER" keyword.
Refer "Security Server RACF Macros and Interfaces", section "IRRADU00 record format".