Oversized heads help achieving cartoonish look. I've stolen that style from Dark Seal/Wizard Fire arcade game. Regarding blurry head look: too lazy to set up a proper palette, so just converted it to 8bit from the sketch.
Agreed with eishiya, the face doesn't look like it belongs on the body
The face looks great, but it's in a different style from the rest of it (much softer and more realistic), and it looks oversized for the rest of the sprite.
Oversized heads work when the stylization looks intentional. In this case, because the proportions on each part look fairly realistic aside from the mismatch, it doesn't look intentional.
I think the head could use some clean-up to make it less blurry. Just because downsampling gave you this result, doesn't mean you have to keep it as-is. Give it some love.