It seems a bit dark, so I would do a larger chandelier with more light. And keep whatever it is, art or wallpaper, light and bright. No dark colors here.

Agree with above before I spent time and money on decorating the walls I would get a larger fabulous chandelier there and then let the style of the fixture dictate what you do on the walls

A new light hands down.

Yes to a more striking chandelier. I like something like this for the wall facing the stairs. Black and white or sepia with wide mats is nice for family photos, or you could opt for something like the infamous Audubon bird prints if you want a little more color and perhaps fewer, larger prints. You can download them for free from their website, or you can buy edited prints from places like etsy.

https://www.audubon.org/birds-of-america

For sure a more decorative ceiling light. The stairway looks kind of dark...how about a mirror to brighten things up?