Black desktop, mouse. cannot change desktop color or background

I just installed lubuntu core on a minimal Ubuntu system. Everything went fine. When I start the computer, I get a login screen with a background. I enter credentials and I can see it loading the desktop environment. When the environment is loaded, the background disappears.

The mouse cursor was black but I solved that by installing dmz-cursor-theme. Now I can see a mouse cursor.

I also notice that menus are black with dim, gray text. When I try to set the background color for the desktop, I can see it saves my changes in the editor but the desktop never changes.

I thought the core package would have the mouse graphics and whatever I need to set a desktop background/color. Obviously, something is missing. What do I need to install?