One of my twins has canines but no other teeth yet, I asked their consultant about it and they said some kids teeth just come through in a random order and had no concern about it
My daughter had a dentist appointment and she has the bottom two and the same top two are coming in nothing on the right she said it happens. She’s a year old so your son has more teeth than my daughter did at that time! All babies are different
Super normal from my experience, eventually they come through. Order can be very different to the ‘expected’