why you should write stuff down and document things
You’re right, your life and ideas probably aren't that interesting.
The number of people who care to know what you’re doing, thinking, and feeling? Very few.
But consider this: historians and scholars today nerd out over old written artifacts. It’s a clean window into the past. Official accounts of the past are often produced with a particular point of view, the heavy hand of the state or the victor looking over the author’s shoulder.
But you? You are free to look and describe things as you see and understand them.
It’s not clear how much that’s on the Internet will persist, or for how long. But there’s a decent chance that your individual perspective could survive centuries even though you're “just a common person.”
What you wore, where you went, how you spent your time, what you worried about, how you lived—all straight from the source, as a gift for posterity.
If nothing else, the people of the far future will be thrilled to hear from you.