There are two issues at work that are causing your results to be a little soft:

• Diffraction Since you are using an EF-S lens it is safe to assume you are using a Canon APS-C camera. Most of the recent models have pixels pitches that cause diffraction to begin at around f/6.8-6.9. This is the point at which the affects of diffraction begin when viewed at the pixel level. As apertures are narrowed beyond the Diffraction Limited Aperture (DLA) the results get more and more noticeable at normal viewing sizes. The best way to avoid this is to shoot at around f/8 or wider and at f/6.3 or wider if possible.
• Slow Shutter Speed Rare is the photographer who can handhold at 1/15 second and get blur free results at the pixel level. You may get useable results for viewing at smaller sizes such as 8x10 or so, but nowhere near the equivalent viewing size of looking at part of an image at 100% on your monitor. If you have an HD (1920x1080 pixels) monitor that measures 23" diagonally you are viewing images at 96 ppi. That means an 18MP image viewed at 100% is being magnified at the equivalent of 54x36 inches!

By reducing the aperture from f/22 to somewhere around f/5.6-8.0 you will be able to increase your shutter speed to around 1/250 second which is much more forgiving when hand holding a shot using a focal length in the 18-50mm range. For the sharpest results you should always use a tripod. And even when you do all of that correctly, the EF-S 18-55mm f/3.5-5.6 IS II is a decent lens but it is by no means the sharpest available at those focal lengths and apertures.

Bear in mind that most of the amazing landscape photos you see at sites such as 500px and flickr have extensive post processing applied that tends to sharpen the results compared to how the image first looks straight out of the camera. In some cases advanced techniques such as focus stacking and highly detailed lens correction are being applied.