ok - let's start a bit unusual - would you share what was end goal that you had in mind when taking them and what do you like the most in the end results?
My goal is to get sharp detailed images with macro. I am going to be purchasing a new camera hopefully soon. I will be doing a slight upgrade to the D5500 which I'm hoping will help with getting sharper images since it doesn't have the anti aliasing filter. My images seem to lack detail which I try to make up for with editing but I feel it makes them look even worse. So I'm hoping the upgrade will help with taking sharper more detailed photographs.
As
@jake337 pointed out your camera is fine. You can go and purchase better one if would like but D5500 is perfectly capable of taking tak-sharp photos. From your photos actually - the photo of the butterfly is really sharp (maybe not perfect but close to). However it has too much per-pixel contrast due to flash pointed directly at the object.
If you want to take really sharp images take into account that in macro photography even if you shoot at f16 you still get very shallow DoF. This means you can't use techniques such as focus lock and recompose. You need to take the photo as soon as your AF locks in or use manual focus and this will bring more challenge to your composition. Even if you move a millimeter since your focus locked before you take the image - the end result will be blurry.
In order to increase DoF - try shooting with closed down apertures - start f5.6 which is the sweet spot for crop sensor cameras before diffraction starts to kick in and then go to f8, f11, f16 - you can compare the difference between DoF and picture sharpness as you go down.
Next is your shutter speed - as you are shooting with flash use your max sync speed with the flash - it's usually between 1/200 and 1/320 sec depending on the camera (not sure which is it for D5500 but you should know of consult your camera manual). If your surrounding is dark enough and you're using f8 or even more closed down aperture your exposure will effectively be the duration of your flash. Lower down the power of the flash and you'll get shorter duration - which will help in taking sharp focus without "motion blur". If you're shooting without flash consider that your shutter speed when shooting macro should be at least twice as high as your lens focal length. So for a 100mm lens on 1.5 crop body (D5500) you get a focal distance of 150mm - make sure your camera shutter speed when shooting macro without flash is at least 1/300 sec.
If your lens has IS - use it, it can make the difference between perfect image and a ruined one.
Practice your shooting technique and steady shooting - try to lean on something sturdy (e.g. a wall) when you shoot - this will minimise any shake on your end. If this isn't work - try shooting with tripod at least in the beginning until you get more comfortable.
With these tips in mind - go ahead and try some more photos and share the result with us.