We apologize for the delay, but we were able to get a list of the default assets for RPG Maker MZ.
Here is a link to a Google DOc with the information. There doesn't appear to be a way to upload files here, hence the link.
https://docs.google.com/document/d/1Cdz7Sv96ZpcbuyszchiDzEQ9mD1RuD7lvtmYxMosNK4/...