Can I use DearestEllie without the AI entirely?

Yes, completely. The Family Archivist is a helper bolted onto the side of the archive, not a foundation under it. Every feature — memories, chapters, timelines, invites, Present Mode, books, exports — works exactly the same with it off, and off is where it starts.

Plenty of families never turn it on, and the archive doesn't nag them about it. If it's not for you, you'll simply never see it.