It sounds to me like you’ve got a very normal dog! That’s a good thing!
A dog communicating to the other object, whether it be another dog, adult, child, etc.. might be occurring more if you are apprehensive about letting your dog visit the other object. It might be that your dog is restrained and wants to get the attention of the other object because your dog wants the other thing to come to it.
It actually sounds a bit better than normal that your dog doesn’t continually bark and bark and bark at the other interesting thing. Beyond some people just not having an interest in dogs, I don’t know of anyone who likes a dog that barks non-stop.
You’re in a very normal position however. It’s the right thing to do that you aren’t just letting your dog run after whatever the interesting thing is, while barking, because it’s going to scare the other dog, adult, or child and turn them off from wanting to play at first.
My advice would be that if your dog barks once or twice at the other dog, adult or child, you can verbally ease the persons mind by saying
“He/She is saying hello, and wants to play”.
You might get a better response from whoever it is on the receiving end of the situation. Most importantly, you are now giving the recipient the cue that it’s their turn to either let the playing happen, or show that they truly are not interested.