I'd think there are a couple of things going on here. The jumping and pestering is in dog terms a bit rude for a puppy this age -- if h is giving lots of social time with older dogs they will naturally discipline this type of behaviour with warning growls or snaps (this is NOT a fight and is NOT an attack on a puppy -- simply dog language for 'you are really rude and getting on my nerves).
If he is still doing this the typical cause is lack of plenty of direct socialisation -- eg off lead, for a good period of time, with friendly adult dogs who will put a halt to this directly and swiftly! If he only is briefly meeting dogs on a walk for sniffing greetings then he isn;t getting enough real socialising. I'd look for some opportunities daily if possible for off lead play. Even other puppies the same age will tend to halt this kind of thing by this age amongst themselves as it IS annoying and with a poorly socialisied adult, could lead to an actual fight -- hence getting this resolved in this naturalway is the best approach. No human can duplicate the handy inter-dog behaviour training that comes from letting young dogs learn from their elders!
But the jumping up is very different from sniffing and licking -- WHICH IS NORMAL behaviour when dogs greet each other, You may also notice that dogs often will lick the urine marking left on a tree or wall as well -- this is a normal way for them to get info about the dog that left its calling card! Sniffing at the groin and butt is a FRIENDLY dog interaction and should always be allowed. You will typically notice tails wagging on both sides as they do this. Lots of dogs will also lick at the genitals for the same reason they lick urine deposits from other dogs -- it simply gives them info. Try to prevent these normal greetings and owners accidently teach their dogs there's something wrong with friendly, info-gathering greetings that are the norm of canine communication and this can directly lead to a dog that gets aggressive or is seen to be aggressive because it doesn't correctly read dog language, appeasement behaviours, etc.
Neutering isn't directly related to this but if you have a male that is overly friendly I would agree that neutering helps curtail overly rude and sexual behaviour towards other dogs. My trainer friends at Dog Training Ireland would recommend neutering for this and other reasons anyway particularly with male dogs. I have fostered and managed countless rescue cavaliers over the years and have always seen a major improvement in really pushy behaviour towards other dogs from males, once neutered, so I'd have a different view on this.
Now would be a very good time to do a group obedience or activity class (if you have done 1st level group obedience already) so that your dog gets some wide-ranging and supervised socialisation (look for a class run by an APDT or CCPDT qualified trainer -- websites for these organisations have lists of trainers by regions worldwide). A trainer will help you undertsand what is acceptable and normal behaviour and what isn't, and how to manage both.