My best wishes to you in your project. And I commend you for making the effort to educate yourself in Linux basics by reading that Rute book. IMO, a common error that is very evident around here is proceeding without having very much of that kind of knowledge.
P.S.: The ls command, or program, is provided by core-utils which any Linux system, big or small, will have. But less (a text viewer and pager) and lynx (a text-based browser) are different matters. Those are separate applications that your minimal Debian disk may not provide. I don't really know, but it is at least a possible explanation for what you described.