[Context: In the seven years I've been living in the Bay Area, I've attended two Rationalist Solstices. Both times I basically hated the experience. I don't really know why, but in thinking about it I think I've understood something worth saying about rituals and symbolism. (I don't think what follows is a crux for me about Rationalist Solstice (I don't even know if it applies); I'd guess that has more to do with people gathering in large groups in general seeming harmful, distortive, or hostile or something.)]
On Friday evening--Erev Shabbat (= evening of the day of rest)--Jews light candles and say a brachah. I was told by adults that this is done to symbolize a separation between the week and the holy Shabbat. On Saturday evening, when Shabbat is over, Jews do Havdalah (= separating): they light another candle; smell spices; and say more brachot. I was told that the warmth and light of the candle serve to remember to us the warmth and light of Shabbat as we enter the week; and the spices, to carry the sweetness of Shabbat. On Sukkot, they build a sukkah (hut) with a roof of loose branches. That way you can see the stars and be open to the universe.
Nothing terribly wrong with all that, but it's not what the candles are for. Jews used to light candles on Erev Shabbat because they wanted to have light in the evening, and they couldn't (by the prohibitions of Shabbat) light candles after it got dark. They lit candles on Saturday evening for the same reason, just after Shabbat had ended. They ground or heated spices (and drank wine) as part of the evening meal just after Shabbat, and maybe then secondarily to show to people (create common knowledge) that the prohibition against grinding or heating things is lifted . And the sukkah was a makeshift hut farmers used during harvest, maybe for shade, or to watch over vulnerable ripe crops at night.
A definition of ritual this suggests: A ritual is a form of an originally purely functional action, stereotyped and exaggerated to strengthen an effect on observers that the original action already had. Stereotyped--as in conventionalized, meaning that the action is done with some incidental features fixed; e.g. grinding spices could just as well have been grinding something else, but it's stereotyped to be grinding spices, and that secondary feature takes over the signaling role (so much that the spices aren't even usually ground (let alone heated)). Exaggerated--e.g. the Torah isn't just read, it's chanted out loud, up front on stage where everyone is gathered, with a whole rigamarole before, during, and after, making it very very clear that something important is happening. Effect on observers--e.g. threatening stances in ritualized animal combat playing off fear of an actual attack, or prohibitions against burning things being lifted by people seeing an authority burning something so they know it's ok now.
This contrasts with rituals that are created like this: there's a message that someone wants to communicate, so they choose actions which obliquely "symbolize" the message; or, someone wants to make a ritual which is "resonant", so they choose actions which are "symbolically resonant". I'm not aware of liking rituals that are made this way. Not that anyone asked me, but my recommendation to people trying to create rituals would be to focus on things that either are overtly communicative (such as reading the Torah, or some of the speeches in Solstice) or are actions that are good to do apart from any symbolic/communicative meaning, e.g. because of the non-social effects they have (such as, IDK, building a house for someone, or something).
 This is sort of speculation (esp. the part about grinding). See https://sci-hub.se/https://www.jstor.org/stable/23255448 , p5-6 (labeled 63-64), Hayim Donin, "Havdalah: The Ritual and the Concept"