> How does someone who has never built a SPA before, let alone ever build a web application in Clojure/S suppose to get started?

I think that Clojure for the Brave and True[0] is a good place to start for Clojure in general, while Web Development with Clojure: Build Large, Maintainable Web Applications Interactively[1] covers the web app side of things.

[0] https://www.braveclojure.com/

[1] https://pragprog.com/titles/dswdcloj3/web-development-with-c...