I had a similar situation and came across... "Pinta" (Linux), I think it was. Did enough while retaining relatively simple and straight-forward controls. (It was no Paint.NET, but neither was it the beginner-adverse Gimp.)

I'd have to have another look to refresh my memory, and it was only a brief need, but might be worth having a look.

P.S. And of course, for vector graphics, "Inkscape".

And, oops: I see now that someone else mentioned Pinta already.