There can be several different reasons why your dog seems to lick everything.
From Veterinary Medicine:
A dog's constant, repetitive licking of objects or surfaces is a problem whose frequency is difficult to determine. This licking may occur often, but because it seems harmless and may only be somewhat annoying, many owners accept this unusual behavior or simply ignore it. However, some owners will inquire about it during a routine checkup and ask for advice.
Such owners often describe a dog that licks floors, carpets, walls, furniture, its own lips, and even the owner's legs, hands, or arms constantly. When not a result of an underlying medical problem, the behavior is unlikely to cause harm. However, if hair and fibers are ingested, constant licking can potentially result in life-threatening intestinal blockage that requires surgical intervention.
The article linked above helps identify different reasons that a dog might lick things excessively. There is also an ASPCA article on compulsive licking in dogs:
Dogs display many different kinds of compulsions, such as spinning, pacing, tail chasing, fly snapping, barking, shadow or light chasing, excessive licking and toy fixation. It’s important to note that normal dogs also engage in behaviors like barking and licking, but they usually do so in response to specific triggers.
There are varying opinions of why dogs might excessively lick things, which can be an indicator of medical or behavioral issues. Personally, my chocolate lab licks people all the time when they first come into the house, and if he walks by you - it is just his way of saying hello.
If you are still worried about his licking, you can always talk to your vet on your next routine appointment.