You've hit the nail precisely on the head when you observed that injecting color into a largely black environment provokes too much contrast. I've experienced that phenomenon with all-black furniture and a highly textured red area rug. Way too graphic. However, wooden objects (and we seem to collect lots of objects made of wood) with natural finishes introduces some warm color that does not overwhelm. And many of the wood pieces have, in their grain, elements of black, so there is a reinforced affinity rather than a stark contrast.

I love @honestday 's suggestion. Bring in some plants, rustic woods and earthy tones.

I like to warm up black with creams, tans, and browns, texture, and natural or rustic elements.

For example add a seagrass or jute rug, Cream colored wool or cashmere pillows or throws, a farmhouse table or rustic African stool. A light colored marble or a metal piece could add another texture and some shine.
If you want to add more color, something like a kilim rug would incorporate into the room without being too stark.

Wood, dark neutrals like charcoals, just keep layering!

throw in grey and yellow, that grey will provide to between to blend the black and yellow so it wont look too contrasting, and the yellow with the red will go well, as long as you edit and keep it from looking like a mcdonalds. But the balance of the two "cools" or black and grey will go well with the two "Warms" of red and yellow. good luck.

I also think add some fun colors as well as other natural materials to offset the black th way that brick wall already does. Sounds like a fun challenge.

You already have two colours, black and brick. It would be easier if you only had the black. I would paint all the walls and the brick in white and add just a bit of colour, maybe a cushion or two, a throw, in a colour you love. I would do a rug in a plain, no pattern, shag, maybe cream.

An easy color palette consists of 60% wall color, 30% upholstery and fabrics and 10% accent color. I agree, black goes with most everything...so that is your 30% color. Take this Stylefinder Quiz to define your design style (traditional, modern etc...) use the 2 (your style and your love of black) to select the right, complete color palette for you.

Just add more color as accent - gray, blue, green - and the power of the red becomes less. I've got dark gray upholstery and a red wall and I added a bunch of blue accessories (pillow, throw, etc) and a small nod of red to pull it into the room and it all balances out nicely.