Some of them are right.
Glad you posted a pic - he is soooo cute and those serious eyes - what a honeybun!!!
Our youngest is/was like that. Very watchfull, thinking going on in there for sure. Stubborn little cuss! Didnt want anyone cept his moma to hold him.
Now hes 18 and pretty much the same. Always pretty serious. AND he’s known that he wants to be a cop since he was a youngin and is going to a college for a criminology degree prior to joining the force. I still dont know what I want to be…
When he was about 4 a gal said his was an old soul, it really does fit.
My Dad tells me that I was very much as the OP describes as a baby. I’m now 23 and extremely laid-back and happy-go-lucky, with a stupid sense of humour.
some kids are old souls. we have 2 in the family that are just short of a year apart.
at 2 one wanted to be a dentist, the other a power ranger. it continued as they got older. the old soul is serious and goal oriented. the younger soul just goes with the flow and doesn’t know what to do when the dreaded grown up time comes along.
My daughter was a very serious baby and toddler. Video of her 3rd birthday party shows her studiously opening her gifts and solemnly thanking everyone. She grew into a thoughtful child and then a vapid, empty-headed teen whose favorite witty phrase was “Huh?” Now, at 22, she is an intelligent and well-spoken young woman, a Certified Nurse’s Assistant sought after by employers for her patience and compassion with geriatric clients, a great favorite of her clients’ families and popular with her friends.
So far, so good.
Wouldn’t it be great if they both started dating … after meeting at the 2032 Nobel Prize conferring ceremony!!! 
A former classmate of mine had a beautiful baby girl. Great big brown eyes, curly brown hair…but with a perpetual look of surprise–bordering on terror.
No kidding, this kid always had a look on her face like she just pooped garter snakes.
It was just her normal look. Shock. Sometimes she’d giggle and burble, but in a few moments her expression changed back to the Holy Shit! look.
I haven’t seen her for a couple of years. She’d be about 6 now. Bet she freaked out her kindergarten teacher.