Connections from character creation are great- it gives the players something to have fun with. "hey we're cousins! We can make up and reference family gatherings etc."
But as the GM ( or player actually) the valuable and memorable stuff is what happens during the game.
But I'm also the kind of GM that will not use a character origin/backstory if it's longer than a paragraph. I won't remember it, and because it didn't happen in the game I won't think to incorporate it since I'm very improv-heavy. It just won't make its mark on my brain like stuff that actually happens during a session would.
This is where the narrative game cooperative character/setting building comes in, yeah? Like you, the usual character backstory stuff bounces off my brain unless I make an effort to grab it. In Stonetop / Homebrew world / Daggerheart / etc, that conversational back and forth with set questions for the GM to ask means you’re having a multi sided discussion about the character. Now I’m invested in the character because we’ve all built them together, spurring each other on and figuring out where things fit.
Stonetop “cheats” because all of the playbooks also have areas where they define the setting, so the GM has all these deep actionable links to drill down on. In my session prep, I jot down a handful of questions for the different characters based on what they’re likely to run into in the fiction to sustain the process - and then in the moment improv and IC flows naturally from what came before.
I’ve started using some of the techniques for my 5e/4e games and the player response has been immense. My personal experience right now is when you prompt with open ended questions about player drives and actions, you get better IC results when the subsequent exploration / RP comes up because it’s in their head already. Also it turns out a lot of people really like have genuine direct influence over the shape of narrative?
Quick example of the above: in my trial 4e game the players are rallying parties in a vale to fight off encroaching mercenaries. The fiction has been established that one character is from a small tribe of shifters in the neighboring forest. I asked them to tell me what that tribe would require for people to prove themselves, about some characters that’ll stand in their way, and then the rest of the party some additional worldbuilding stuff around that.