Oh, you know I did not read the error carefully, I guess.

It just said that it could not drop the schema because of the tables within it, so it seems, so I reran the command with CASCADE at the end and that did the trick.

Unfortunately, like I said, I totally messed up the Java installation on that Mac machine (while attempting to upgrade to the latest one), and the setup on Macs is way more involved as compared to Ubuntu, so I do not have the necessary knowledge in order to fix the issue: 'java -version' prints fine, but neither the Java Applet Plug-in for Firefox, nor Tomcat work correctly and the Java menu window in Settings does not open either...