I totally agree with this analogy, though maybe to add some nuance (or pedantry), I'd claim that to start learning Chinese, you need to pick a modern dialect (probably Mandarin), which is like choosing Spanish over Portuguese or Catalan. Then, learning Japanese or Korean (or Vietnamese) is like learning a nearby but non-Romance language that was heavily influenced by Latin or Romance languages, like English. Knowing Spanish will let you appreciate the similarities with English, but you'd still need to delve into historical Spanish (or French) to really see the connections.

Chinese is a pretty old and continuous language, so at the advanced level, learners could delve into Classical Chinese, which is truly analogous to Latin, and was also a dominant lingua franca in written form across East Asia. Pieces of Classical Chinese are 'alive' in everyday use, kind of like how Latin is 'alive' in the Romance languages through general and obvious similarities, or specific vocabulary, (e.g. "quid pro quo", "ad hominem"). But Classical Chinese is radically different from any dialect of today's vernacular Chinese.

In any case, the similarities and overlap definitely make learning between CJK(V) easier!