Even I tried playing around with the manual mode, and many times I shot scenes with fastest shutter speed and widest apertures, but still the image came out to be as dark as difficult to discern it. I did a research on it and found the answer as very basic simple fact of optics.
Human eye is very much sensitive and flexible to changes it needs to do, to see clearly in sudden changing optical conditions. And human eye can even see in darker realm to some extent. But camera is not that sensitive, the exposure of an image entirely depends on the intensity of light falling on sensor for a particular span of time. So what we see a scene and interpret it as brighter may not be brighter for camera, and hence what we deem the light as normal day light may not be sufficient for the camera sensor to impose an image on.
Manual mode is one of the ways to implement your creativity in photography for advanced users, but they should also have an external metering device to calculate the intensity of light at different place comprising the scene, to be sure of the fact that the amount of light (they can see) is intense enough to expose on camera sensor as well, a sharper and brighter image of the scene being shot.