I noticed that there are a lot of "beginner" resources for LaTeX, lots of novice friendly tutorials etc.
Are there similar resources available for Plain TeX that are geared towards beginners?
Please note, prior to answering, that this question only relates to "Plain TeX".
To the best of my research, all of the TeX.SE existing answers setting out beginner resources deal only with "LaTeX".
The answer: what-are-good-learning-resources-for-a-latex-beginner is great for people who want to learn LaTeX. It does not however address those people (including me) who want to get started on learning Plain TeX.
The answers given so far are well thought out "Plain TeX" beginner resources.
Related: Transition from latex to plain tex