settle
is designed to be as usable to humans as possible.
Zettel don't have any sort of IDs, and are instead referenced only by their title. Using unique IDs like other apps do would be a poor choice, since it's astronomically unlikely that you'd have two notes with the same title - and even then, it's not worth sacrificing the readability of the entire system for one or two peculiar cases.
Moreover, tags and links are embedded within the Zettel's contents themselves, allowing you to easily give more context to your connections and ideas.