It is worth looking at in a bit more detail. Look for a white border (not always obvious but the info at the bottom of the main window shows what is active)
(1) The basic layered image, shows as background. (Please, do not try and make Gimp look like PS, it does not help for new users)
(2) An intermediate layer (white border) moved with the move tool.
(3) A layer with layer mask (note the white border) and layer + mask moves.
(4) Now click in the layer mask icon to activate - shows as mask and has a white border. That edits as any layer including moving,
(5) For Gimp 3 chain Layers together, ctrl-click in the layers dock. and transform move / rotate / etc. together.
(1) The basic layered image, shows as background. (Please, do not try and make Gimp look like PS, it does not help for new users)
(2) An intermediate layer (white border) moved with the move tool.
(3) A layer with layer mask (note the white border) and layer + mask moves.
(4) Now click in the layer mask icon to activate - shows as mask and has a white border. That edits as any layer including moving,
(5) For Gimp 3 chain Layers together, ctrl-click in the layers dock. and transform move / rotate / etc. together.