Lights not casting shadows/UV mapped images dark I am trying to simulate a small setting in a casino in Blender. I have a cube that has a green felt texture mapped to it (it's my table) and I have some playing cards on top of it (they are also textured with an image).
A couple of problems that I think are likely related:
So far I have been setting the textured surface on all the objects as Background Why? Because they show up nice and bright. If I use the default surface mode, I think Diffuse BSDF or Principled, the textures show up very dark.
I started playing around with some objects here because I’d like a realistic-looking scene with lighting directly overhead and my table or cards with textures aren’t getting lighter/darker nor casting any shadows.
I see people talk about a cast shadow or shadow option. I don’t see it. I see something called, contact shadows. I have a feeling that’s not it.
Stumbling around some forums I saw someone posted about “World lighting?” So I clicked on the down arrow under options for Viewport Shading. I unchecked Scene Lights and Scene World - doesn’t seem to help.
What else can I be checking for to figure out why…

Shadows aren’t showing
Texture mapped images aren’t getting lighter or darker depending on the light location
Why initially are the texture-mapped images are always dark unless in background mode.

Thanks.
It sounds like you need more/better lighting in your scene. Without light sources in the scene, the only lighting is the very dark world background which doesn't emit much light so everything looks very dark.
Additionally, shadows are very weak as what little light there is is coming evenly from all directions. Background shaders actually emit light (as you want the background to do, it simulates light coming from things outside your scene) which is why that makes the objects brighter, but I am guessing you don't really want all the objects in your scene to be emitting lights.
Try adding lamps (or emission materials on appropriate objects) in logical places in your scene.  If you could include some screenshots of your setup then we would be able to help your case more specifically.