Does the shelf come out? If so, you could try nothing above the TV. If not, and you want to use your Mom's piece, just add some books horizontally to the other side to keep it simple. Too many items will distract from the TV.

Back the heck up and take another picture. We cannot get a feel for what you are asking with what you gave us.

Would be easier to offer advice if there were photos of the entire room.

I need to see at least that wall where this is .

Looks like it’s part of a bookcase, so suggest creating a connection vs adding random items just to fill and balance/repetition are key.

If you’d like suggestions, provide a picture of that entire area.

Maybe include just your mom’s piece there and place the pottery on another shelf as they are competing.

That cabinet space sounds like a great spot to lean into the rustic feel without competing with the TV. A few ideas:

Go asymmetrical rather than centered — group the pottery piece and the blue urn together on one side (odd numbers of objects tend to look more intentional than pairs), then balance the other side with the antlers laid horizontally or mounted low so they don't pull the eye upward toward the screen. Stack the books flat in two or three uneven piles and use one as a riser under a small piece — instant height variation without adding clutter.

Keep a bit of negative space around the TV itself; if everything is spread evenly across the whole 47" width it'll visually compete with the screen. Grouping items into a couple of "vignettes" with gaps between them usually reads calmer.

For color, since you're already brown/blue, the wood pieces will bridge the two — maybe flank the urn with a couple of the smaller wood pieces so it doesn't sit alone.

If you end up wanting a small accent light for that shelf (a lot of built-ins like this look better with a bit of warm uplighting rather than straight overhead), I found a decent rundown of options here: gardenandhomereviews.com/furniture-decor — not essential, just handy if you want the display to pop a bit more in the evening.

The shelf is fixed. Here’s the big picture. This is a vacation home that we just moved into so there is not much on the adjacent bookshelves.

Probably not what you want to hear, but, here goes. I'd rip the whole thing out.

Wallspace is too valuable to be wasted on that huge piece that will cost you $$$ to decorate the shelves perfectly.

Buy some old books and line ‘em up. Make it a solid “wall” of antique binders and it’ll look better. @oncape had a pretty great idea, but probably one that you don’t want to hear…