Can you explain how conflicts are not conflicts?

If I change a line of code several times and rebase on to a branch that changed the same lines of code, how are you sure what the right one is?

JJ can save conflict related state with the change so that you don't need to resolve a conflict in the middle of a stack of changes for rebasing to continue for the remaining changes. Concretely, it uses a "conflict algebra" where it can track the impact of a conflict as it propagates through the stack of rebased changes: https://docs.jj-vcs.dev/latest/technical/conflicts/