The mouth and nose seem fine (although the lips might be able to use some more depth), but the main thing that’s detracting from it is the lack of protrusion of the eyebrows.
The eyes are essentially “sunken in” on humans to protect the eyeballs from damage. You can put a flat plane from the eyebrow to the cheekbone, and it won’t touch the eye. The forehead slope is fine, but it needs to come forward with the eyebrows.
Another thing is the ears sit just behind the jaw, with the top of the ear in line with the eyebrows, and the lower part of the ear normally lining up with the bottom of the nose.
It looks like you have the basic proportions right, but I’ll relist them here anyway:
The distance between…
Chin->Bottom of Nose
Bottom of noseNose->Eyebrows
Eyebrows -> Hairline
Are all equal. In addition, the eyes are half the distance from the chin to the top of the head (It seems like our eyes are in the upper part of our head, but it’s an illusion because of the hair line… they’re in the center).
Another thing I noticed is that the little groove that extends from the upper lip to the bottom of the nose looks kinda funky. It usually gets smaller towards the nose and ends up being the same width as the distance between nostrals.