I love my Solomon's seal, huchera, hydrangea, hostas and local native shade-loving perennials. Check out what grows naturally in your zone for some plants that will thrive in your conditions. Also put in some bulbs for spring while you're at it. I border with monkey grass that is easily divided to share with others.

What zone are you in? I don't have experience with burning bush. If you need ground cover you might take a look at www.steppables.com to get some ideas.

We plant pretty close to our trees. Heucheras are fun b/c they come in some cool colors-we've got silver w/purple-y veins, bright pink, some fall colored ones, lime green...different sizes too, some are big, some small, and they flower nicely.

https://www.thespruce.com/best-perennials-for-shade-2132599

Stick some in the ground and let them make their own plan. Sometimes I dig them up if they decide to take more space than I want them to. Natural local plants that are perennials will take care of themselves. You just have to keep them in check.

Lowe's has them. So will your local garden center.

Nothing at our place is perfect and symmetrical. Who has the time or money to achieve and sustain perfection? Not I! Besides, what in nature is eternally perfect? We've moved so much of our stuff so many times, changed our minds so many times. (ahhh the wonders of hostas) This is what I posted many months ago about how our planning has gone over the years. Sometimes you just gotta embrace it and run w/it.

I would add some Athryium ‘Ghost’ ferns. They have a silvery appearance and make an area pop. You can mix the ferns with other green foliage plants for contrast. By the way you might consider Hostas boring but they would work well with the ferns.

To echo everybody else just plant your choices in what you think might look good. Some things will work and others not so much. I rarely have a plant that stays in its original location.

The space has lots of potential. Good luck!

Here are a few more.

Hellebores, Brunneras, Pulmonarias, Gingers (Asarum), Heucheras, Tiarellas, Heucherellas, variegated False Solomon Seal, epimediums, dubia, Carex Gold and variegated forms, Hakonechloa, Anthriscus sylvestris 'Ravenswing', Ligularias, Actaea/Cimicifuga, Ceratostigma plumbaginoides, Toadlily, Mayapple, Kerria japonica, Sarcococca, euonymus, (Burning Bush is considered an invasive), viburnums, Leucothoe, skimmia, mondo grasses, Spigelia marilandica, corylopsis, pachysandra procumbuns, kenilworth ivy, pachysandra variegated, columbine, wood phlox, astilbe, hardy geraniums like 'Samabor', bergenia, astrantia, lamiums, ajuga, dicentra, fatshedera, sweet woodruff, strawberry begonia, begonia grandis, lilies, doronicum, vancouveria to name a few.

'Dubia' should have been 'Jeffersonia' dubia.