[Gimp-user] How to do a simple erase

[The Tick <the tick gmx com>]

I'm using Gimp 2.8.22, win7x64

I managed to create a simple square "brush" since I saw nothing but 
fuzzy brushes by default. When I use the eraser tool, select my square, 
set the size to a nice big square and then drag the mouse, I get a very 
large stairstep as I drag. I experimented a bit more but now I cannot 
even get that -- it's erasing some sort of checkerboard pattern and not 
even 100%. So now I seem to have even broken the default settings.

How do I do a simple "erase" like other paint programs where I just drag 
the mouse and the area under the brush is totally erased?

Googling for "erase leaves stairstep" and other searches I tried led 
nowhere.