UM22.04.3
HI, found this but doesn't seem to address you wanting bookmarks at top, seems like the default bookmarks are hard coded and in link he hides some which just move the bookmarks up.
https://ubuntu-mate.community/t/how-to-edit-the-default-places-and-defaults-bookmarks-in-mate-panel-and-caja-side-panel/10932
Possible two click workaround might or might not be helpful for you.
On right I chose Bookmarks from dropdown arrow (I don't have any)
On left I chose Places from dropdown arrow
Quick click no changes made to system.
Edit: Not sure but think you could bookmark replacements for the default places.