Looking back, there were so many other options that I missed, but my initial projects with MySQL have taught me a lot about SQL databases.
DB2 though I was not a full time DBA. I managed the operational systems and security side of things and worked with the DBA's quite extensively. After that was mostly Oracle and mostly dealing with testing backups, managing disaster recovery procedures and of course make it go faster.
Looking back, there were so many other options that I missed
I don't think you really missed anything good. Modern open source databases drew from many lessons learned from the previous databases and in my opinion are much simpler, faster and pragmatic. Some of the more complex features of some of the older databases have since moved into the application stack.
Borland Paradox
Getting into the more modern era... I don't remember exactly... my first job involved some DB/2, but I got exposed to Oracle and MySQL pretty early on as well.
This started in 1986? and by 1990 they still hadn't ditched the old stuff but did a synchronization operation between the two database systems every night. It was sort of like replication but with a serial cable involved. Half the staff wouldn't give up the old interfaces.
Model 204 with COBOL. [0] M204 was a pre-relational database that used inverted indexes to locate rows. It sparked a life-long fascination with data.