The basic model looks fine. He is what he is and there’s nothing wrong with him unless you specifically want to change something but don’t know how.
As far as giving him more “life”, I think that’s going to come down to UV texturing. Once you start adding colour to wrinkles and around the eyes and lips, that’s when the character really moves into the next dimension. Until then, they always look like Muppets.
You could try vertex painting for a little bit of detailing without the mess of UV mapping - but it’s not the same.
Also, and this could be the thing that keeps you going forward, try playing with some facial expressions using RVKs. This is where they get their character. Try a cunning grin, a frown, a smile and a look of shock-horror!
Also, also - lighting. Play with some moody lighting and different coloured backgrounds. Thies egive the model a sense of environment and therefore, of life.
MESH: If you want him to talk, then the mouth may need a little work. In the original mesh image, it doesn’t look like you have much of a loop setup around the mouth to assist with clean deformations. Look at good head models for a guide on how the mouth and lip loops should run. Add lips if you really want to but don’t do it just because other characters have lips.
Also, have you tried to make him blink? This can bring tears to your own eyes if his lids refuse to play the game. Some people use RVK for this but I’d recommend using bones and weight painting in this case. This way you can achive a nice spherical deformation where the lid literally slides over the eye surface. The lids will need enough vertices to allow for this smooth transistion.
I understand your hesitation with UV mapping - I’m still avoiding it too - but your character is almost ready for it I think.