Sort of. They're...everything. They're immortal and powerful and are tied to and represent basically everything. Some are a lot stronger than others. The sun and moon are spirits. Or...have spirits connected to them. The oceans have a spirit, important stages of life have spirits, even ideas. But not all spirits are attached to something like that. They just are, and always were and they live in the Spirit World.

But sometimes people can become spirits. Of their own choice, or if a powerful spirit rewards them with it. There's a ton of folk stories of oppressed lovers and abandoned orphans being turned into spirits.