Kindness and a sense of belonging tend to reinforce each other closely: being treated kindly by others makes a place feel genuinely welcoming, while feeling that you already belong somewhere tends to make it noticeably easier to extend kindness toward others in turn, without the usual wariness a genuine stranger might reasonably feel.
Newcomers to a community often describe a single small act of kindness, a neighbour's greeting, a colleague's offer of help, as the specific moment they began to feel they actually belonged there, which suggests belonging is frequently built through small, particular gestures rather than through any single large or formal welcome.
Communities that are consistently kind to newcomers tend to retain them more successfully, since a sense of belonging, once genuinely established, becomes one of the strongest reasons people choose to stay somewhere long after the original reason that first brought them there has faded from relevance.