I didn’t do many impressive things in my childhood, but I’m confused which topic I write about.
I had tech addiction when I was 2 years old, I used to do a lot of dangerous electrical stuff when I was a little kid, I made a handmade chicken incubator, i made an android app with 50k users, i always dreamed about making a big company, i have won national chemistry olympiad 2 times ( being one of 1000 winners among 40k contrubutors ), which one is better?
To me, all of that sounds pretty impressive. But it is important to know that your essay is less about achievements, which will be covered elsewhere in your application, and more about your character.
The focus of your essay should be one of your core qualities. Judging by your work, you could write a great essay about being a builder or inventor. That theme would serve as the center of a story about your growth as a builder. And all of the above work would become the elements of the story.
Hope that is helpful.
Chris