Upload & Sell: Off
Question isn't so much one of gear/technique or post processing, of which your using a pretty cheap kit zoom, stopped down to the point where diffraction is an issue, at slower shutter speeds with IS perhaps still active and your not even sharpening the files, but rather one of did you enjoy shooting the images.
Are you happy with the versatility and range of the lens and the money you paid ?
Would you be willing to spend more money and/or lug more gear for sharper photos ?
12-50 isn't a great lens and its not a horrible lens, but it cost just a few hundred bucks, is a useful range and weathersealed to boot.
Its not going to deliver world class sharpness, but was that your goal ? Are you making huge prints, or just posting to the web where its not even going to matter ?
Most important of all, did you enjoy the process of shooting, which for many seems to take a backseat to the results at times.
All too easy to forget the fun of actually being out in the fresh air doing photography rather that sitting inside the house staring at a computer monitor and 100% crops.