Most of the "Resprites" are just recolors or lazily edited versions of the sprites, and any of the more unique sprites seem to have little or no effort put into them, and they're rife with inconsistency(for example, some sprites have outlines and higher resolution, while others have black outlines and are in the standard resolution.) Most of yours are not shaded at all as well.
Your main problem is mixels(different sized pixels in the same sprite), and I'd recommend using Piskel to sprite in 1x1 and export in 200%. Additionally, you probably should look up some guides for basic spriting(I'd recommend saint11, or asking around on TPA/Calamity Art Server), and I'd advise against recoloring sprites. Try to develop a style and stick to that when making your sprites.
Have a good day, and I hope this helps you develop more skill in spriting.