Fictional recon requires that you look at things a little sideways, drawing lines between your life here and the fiction you're drawing on. Sometimes these two things mash up in ways that catch you off guard.
This is my ancestor altar. There are pieces on here that I received from deceased family members, as well as things that remind me of others. I don't have a lot of such things, so my ancestor altar has always been kind of a small add-on to other altars before this iteration.
As I was working on an early draft of a historical steampunk-ish story in the Empty Sky, I started picking up pieces at estate sales and thrift stores that reminded me of one of the main characters, an airship pilot named Jack Rose. I built a mockup of a piece of equipment he uses, just for fun. I played with the idea of building an altar that this character might have had, but he wasn't really the house shrine type.
However, Robin, my primary entry point into the universe, the character who is the focus of my self-insert theory... he's definitely more the type. And he's a descendant of my historical character, so these things could very well end up on an ancestor shrine he maintained.
That's how they ended up meshed equally among my own heirloom pieces, doing double duty. By claiming Robin's ancestors as my own in a way, I honor the history of the world and the spirits of those stories that build the world. No worldbuilding exists only in the vacuum of the present, and just because something is backstory does not mean it is not still part of the story. Second, the other items on my ancestor shrine act as a physical tie to the ancestors I didn't know personally but who are nonetheless part of the backstory of my own life. I don't know all the stories of the people who came before me, but I know they lived and honor their role in the overarching story.
Once again I use Robin to fill in the spaces in my life and I use my life to fill the spaces in Robin's. This is part of self-insertion, finding yourself as a part of the story you're telling. I'm still developing all of my ideas about self-insertion, but it's definitely one of the easiest ways to create a strong relationship between yourself and the fictional paradigm you're working with. Unlike the Mary Sue, your goal with self-insertion is not self-improvement, but connection improvement. The ancestor shrine is just one of many ways to create the paradigm you want to work in.