You probably didn't turn off Ambient Occlusion in the Scene context menu. Do that (and only that) and you get this:

You probably didn't turn off Ambient Occlusion in the Scene context menu. Do that (and only that) and you get this:

Also, if you change the background color to black (AFTER turning off Ambient Occlusion in the Scene context menu), the entire scene will be black (which will not happen when it is on). This signals that changing the background color will now affect ambient lighting