The art for the character looks stretched. If you want a pixelated look, you'll want to change some settings in Unity on the image itself.
Pixels per unit will determine how big the image is. Play around with that to find the right size.
I recommend setting filter mode to point (no filter) so Unity doesn't try to apply anti-aliasing or otherwise blur between the pixels to try and improve the quality of your art.
Setting the format to RGBA 32 bit worked for me to make sure Unity didn't alter the image in any other way.
You get to these options by selecting the image in your Project window. If you have any questions, let me know. It's very helpful to play around with these settings when you first start uploading your art to Unity so your art assets can be consistent.