Firstly, you use MS Paint?!
Secondly, from what I remember from my time using MS Paint ages ago, things can only be rotated using the selector tool, but it's only 90 degree rotations.
A quick workaround I used was by writing things in in Word or Powerpoint, taking a screenshot using sniping tools, and pasting the screenshot with the transparency option* enabled in the drop down menu for the selection tool.
*The "transparency" option in MS Paint works by taking anything that matches the secondary colour and turns it transparent. Great if you're moving a bunch of small things on a solid colour canvas, not sure how it acts with more detailed works.
Alternatively, you can install Paint.net, Gimp, or Krita and have that ability and much more. Paint.net is my go to if you're a MS Paint "veteran". I know I used it a ton before moving on to Gimp and Krita. It's like MS Paint, but...more.