I think at this age they are still doing parallel play unless an older person actively engages them. DS (23 months) does his own thing but will wave at people or say hi. I constantly tell him, "say hi to x" or "wave bye bye to y" or "look at what z is doing"
M is 15 months and her parallel play consists of observing naughty behaviors and deciding it's okay for her to do them. She will hand things to others, and offer food to others, and also stares a lot, but when actually given the opportunity to interact, she often walks off the other way. She does enjoy saying hi to others.
Re: Social