Normal map node doesn’t connect to the displacement input of the material output
The texture you are using in the normal map node is not a normal map texture. convert it to a normal map or bump map before using in a normal map node or bump node
Uh, that’s not a normal map, so your bump is going to be effectively random. You’re likely to get better results by running it through a RGB to BW converter and plugging it into a Vector>Bump node. Be aware, the lighter parts of the image will poke out, so you’ll want to invert it somehow - either using an invert node, a color ramp with the black and white swapped, or just by setting the strength to a negative number on the Bump node. If you have access to Photoshop or GIMP, run it through a high pass filter to make a better bumpmap. Plus, the vector output of both the bump node and the normal map node in your setup should be plugged into the normal input of your shaders, NOT the displacement input for the material output - that’s looking for a black and white image.
Also, I don’t think the Mix Shader node knows what to do with a colour image, although I could be wrong - it wants a black and white input. I’d be inclined to use a layer weight node as an input (plug the bump map into that too), and it will probably do a better job of picking out the highlights than a detailed specular map - I would probably try to make a coarse specmap to turn down the glossiness specifically on the mortar between the bricks.
On a side note, remember that just because you found it on Google images doesn’t mean it’s free to take, even for personal projects like this - although they’re unlikely to come after you with a lawsuit, it’s polite to make sure that you’re not violating someone’s intellectual property rights. Look for images released under creative commons licenses - pretty much any will do for personal work, but if you are doing commercial stuff make sure it’s cc0. If in doubt, go to http://www.cgtextures.com/ .
Creative commons has various licenses. CC-0 means you can use it in all your projects without breaking any law. For example, CC-BY means you need to give credits to the author.
Fairly realistic bricks imo, although I think the scene needs more light.
Another thing you can do if you don’t want to use another texture is to use nodes like separate RGB and separate HSV to extract a black and white map that might get you decent results.
The bumping would be done by information created through the bump node, not the normal map node, as the latter expects a map that uses color information to represent the direction of the normal and as such is being used improperly in your setup.
