One of the things I'm most proud of as a dev is a tiny contribution to the Nim standard library. It's a single commit and very simple, but made the PostgreSQL adapter consistent with the other RBDMSs' adapters. At the time, I'd been using Nim for only a couple of days, but that didn't stop me from being able to contribute in a meaningful way.
I'm amused and humbled that despite all of the work I've done over the past decade, it's quite likely that a seven-line change that I did mostly in ignorance will be the thing that impacts the most people going forward.
Here's the change, if you're curious: https://github.com/nim-lang/Nim/pull/6381/commits/921cc53e40...
My most popular open source project, by the numbers, is a ~40 line Rack middleware I wrote when jetlagged at 2am. ~29MM downloads all-time, 984 github stars.
I think about that all the time.
FTFY. There's a non-zero amount of time investment required to submit kernel patches (learning enough git, using the mailinglist, responding to questions, submitting revisions, etc)
---1.9 Ext4 file system parameters
+++1.9 Ext4 file system parameters(Sadly, at age 53, I probably cannot get away with trying to make letters happy or otherwise be "cute", or I might well be inspired to try to do some kernel dev in the near future.)