Main Photo is not appearing behind objects in Mock Photo (such as plants, etc)

You don't have a layer mask or transparency on the sofa/lounge layer.

Hello, please can you add a screenshot video of that process?  

The way I work is to select and copy all the foreground elements to their own layers.  That way I can control which composited elements are in front of or behind the other image elements.  What you NEVER want to do is composite a new element into an area you have selected on the same layer.  It's even not a good ide to place the composited element above the foreground elements and hide it's background withg a layer mask.

Always fill in with layers BELOW the foreground elements in the layer stack. 

So starting with this image of a lounge with sofa

We select as many of the foreground elements as we need, and copy them to new layers.  The smart way to do this is with layer masks, (but I have applied the masks to make the layers panel cleaner and easier to follow.)  Photoshop's selection tools have become so good it is rediculously easy to do all this nowadays.

By placing each object on its own layer, you can quickly decide what to include or leave out. Or you can replace it.  You don't even have to work on it if you don't mind using up som Generative Credits.