According to the EXIF data the lens was set to f/32, the ISO was 1600, and the shutter was open for 1/3 of a second. F/32, a very small lens aperture, diminishes focus sharpness because of diffraction effects.
The image would have been improved if the lens aperture was larger, say f/16, which is 2 stops wider open than f/32 is. You could then have had the same exposure by lowering the ISO 2 stops to ISO 400 for less image noise, or lowered the ISO 1 stop to ISO 800 and a 1 stop faster shutter speed of 1/6 second, a combination that also adds up to a 2 stop change in settings without changing the exposure.
Perhaps you used those settings intentionally for artistic reasons, but you might realize more significant image quality gains by gaining a better understanding of how photography works, rather than looking to image editing as a solution.
No doubt, virtually all digital images can benefit to some degree by post processing, though some image file types, like JPEG, are post processed right in the camera and are not intended to be processed any further.