handlebar templates technically do not allow you to index directly into arrays. However, I discovered that there is "undocumented" syntax. What does work is children.1.content or children.2.content and relatedly children.[1].content and children.[2].content.

The reason you might want to do this is because you may have separate files that you fill in that drive two different sections of the template. In these cases, {{selection}} is insufficient but you can effectively hard-code any number of hard-coded considered context by simply specifying them as Obsidian links.

You can learn more about this obscure quirk of handlebar.js here: https://stackoverflow.com/questions/8044219/how-do-i-access-an-access-array-item-by-index-in-handlebars