Hey Chungsie! I have a few critiques for you if you want to hear/read them.
TLDR at the bottom
Ok so, my first impression is that the animations of the character are super stiff. From the movement to the anatomy, things just aren't quite right.
I know you can only do so much with pixel art, but there is still stuff like the thickness of the shoulders, curve of the spine, length of the legs (though that may be a style choice) that could read a bit better. A study and understanding of anatomy is super important even in pixel art!
The animation itself has a lot of still parts. Even if it's a punch, you can't just have the arm moving. You need to move the whole body! In my example below I have a run. As you can see every part of the character is moving and not just the legs.
Another thing to watch out for is change in proportion. An understanding of perspective is super helpful here. Keeping the length of each limb consistent (while keeping in mind perspective) will add a lot more believability to the animations.
Then there's stuff like timing. This is super important when it comes to games. Levels of responsiveness differ from game to game, and though I'm not sure what your game calls for, but anticipation is something you should always try to have in your animations. The amount of anticipation depends on how fast you want a reaction to happen. Right now your timing is flat and consistent and... um.. boring. This only helps in giving no weight to your character or his movements.
There's a lot of other animation tips I could give you, but the biggest and most important thing I could suggest is to go online and study the 12 principles of animation. Knowing and understanding this will become the foundation for all other animation tips learned.
Along with animation, there's color. Learning color theory can really help when picking nice colors. After learning color theory, looking at other people's work and see what colors they chose (and trying to figure out how it looks so good) will help you to choose awesome colors too. In my picture below you can see I made myself a swatch of colors to pick from. I came up with these colors through my understanding of color theory and studying others.
There's also shading. Understanding objects in three dimensions is vital to correct shading. Figure out where your light source is coming from, and darken the areas the light doesn't hit. This only applies if your art style includes shading (obviously). For some people, they tend to make the arm and leg farther away (in my example: the left arm and left leg) completely covered in shadow to help separate each arm and leg from one another. This can be included even if you don't have shading on your character (look the animation example compared to the still image next to it).
There is one other thing though. I haven't tried this out for pixel art but I feel it could still work for you if you wanted to try it. It's a bit like cheating, but can still help. Learning stuff like anatomy, the 12 principals of animation, color theory, and so on can take a lot of time, so how can you make better animations now?! Though I certainly suggest you still study these things, you can still cheat by recording yourself doing the action and drawing over yourself.
Your body is already the correct proportions, nice lighting can give you good shadows, and everything will move smoothly and realistically (because it IS real, obviously). Though there are down sides to doing this. You would need a good understanding of anatomy to change the proportions correctly (though this is still better than just guessing). Along with that, regular human moment looks weak, especially when used in animation. Learning what Keys, extremes, breakdowns, and inbetweens are can really help tell you which frames in your recording should be exaggerated, removed, or even have frames added. You could still use your wireframe idea if you draw it over yourself in the recording.
As far as quitting spriting... heck no! Well... as long as you're enjoying yourself you should keep spriting. You're making stuff and asking for critiques. Just keep doing you, you're moving in the right direction!
TLDR: do some anatomy study, study the 12 principles of animation, don't have still parts on your character (usually), keep proportions, keep in mind things like timing, learn color theory and shading, learn about keys, extremes, breakdowns, and inbetweens, and while you're learning all of that you can cheat and draw over recordings of yourself to get better results.
Hope that's helpful dude.