Notepad++ - This is the definitive notepad-related software you’ll ever need. Multiple tabs, keeps tracks of lines, lots of features and preferences. One of the most invaluable parts of it, is that you can close it or a update happens or maybe your PC will get knocked offline. You can come back to Notepad++, open it, and everything will be retained.
Krita is such a horrible crashy mess - most of the time all I need is good old MS Paint (plus free rotate) but I after two decades of Linux I’ve yet to find a paint app that doesn’t overcomplicate everything with layers and selectors and modes. 😭
So, Rhynoplaz was after “fancy” stuff, but okay, I suppose that there’s an use case for a MacPaint/MS Paint analog, with a low barrier to just get going.
Maybe Drawing for GNOME or KolourPaint for KDE? It doesn’t look like either of those support layers. Drawing looks like it lets one drag a rectangular selection to rotate to non-90-degree increments. KolourPaint doesn’t, but it lets one choose to rotate and input an arbitrary number of degrees.
I haven’t used either, myself, other than just to check now. They’re both packaged in Debian, so they’re probably also gonna be packaged in any Debian-family distro.
EDIT:
https://maoschanz.github.io/drawing/
https://apps.kde.org/kolourpaint/
Both describe themselves as being “simple” paint programs.