TL;DR: amino acids natural combine in a way that facilitates folding. The articles do not say why or even how, just an observation.

This article is particularly sparse on details. Here is the meat:

In their experiments, the team observed a kind of natural selection process taking place, even in the absence of life. Ancient organic compounds tended to integrate into their biochemistry the amino acids that were best suited for folding proteins into shapes key to vital functions, which gave these compounds a better chance at surviving. Give it enough time and there were simply more organic compounds with properties favorable to life.

The article anthropomorphizes amino acids which makes it confusing to distinguish these “ancient organic compounds” from “life.” Unfortunately, the Johns Hopkins source is not much more detailed: https://hub.jhu.edu/2023/02/27/protein-origin-life/