You might try Hinoki - Chamaecyparis obtusa.
Look in the woods that are on your property. Look at which seedlings are sprouting and developing well IN THE SHADE. These are the species to think about using.
Also, I've owned by house for over 35 years. I was neglectful at cutting down volunteer trees. Even though I have only a 50 foot by 150 foot city lot, my little plot has become too heavily shaded. For the last couple years, I have a tree service come in and remove a thousand dollars worth of trees. I need to do this a couple more times.
Trees grow, sometimes if you want to see the sun, you got to take one or two of them out.
Now I am definitely not suggesting taking out an ancient giant tree, but perhaps see where removing a couple "adolescent trees" could open a window to the sun for you.
Although, given the way summers are getting hotter, and dryer, learning shade gardening is not a bad idea.
Hemlock, Tsuga, especially eastern hemlock, Tsuga canadensis, tolerates shade better than just about any other species of conifer. However to get tight growth, some sun is helpful. Look into shade gardening books. Some of the shrubs recommended for shade gardening can work well as bonsai. I don't have such a book myself. A little time on the internet would reveal much. Japanese maples are an obvious choice.
Blueberries, highbush blueberries, Vaccinium corymbosum grow well in open shade. Their fruit yield will be low in shade, but as bonsai, the focus is the spring flowers and the autumn color. Many members of genus Vaccinium grow well in shade. Blueberries, dwarf blueberries, whortleberries, bilberries and the several species of cranberries all have some shade tolerance. The culinary cranberry is the one that wants more sun, but the lesser known wild cranberries can tolerate some shade. The dwarf blueberries are quite good in the shade, only drawback is they are quite dwarf, tend to be "wispy", so their visual impact is low, they end up as kusamono more so than bonsai.
Do give Satsuki azalea a try. They get by on less light than one might think. Also look into "forest floor" species of shrubby rhododendrons, not the ones with big leaves, the little ones.
A number of vining plants develop woody trunks, Virginia creeper, Parthenocissus, will survive a long time in shade. Beech seedlings persist forever in shade, growing rapidly when a tree falls and they end up in some sun. Hornbeam, genus Carpinus, especially Carpinus caroliniana can get by in shade. Just an hour or two of sun will get you fairly normal growth.
You either have to fall in love with the obscure world of shade gardening, or you might have to resign yourself to selecting an adolescent tree or two to remove. I love old trees, but there are times when we have to figure out how to work around them.