I came across this interesting video on YouTube, WIKITONGUES: Jack speaking Ladino . If you’re not familiar with it, Ladino is the traditional language of Sephardic Jews who were forced to flee Spain in 1492. It retains many features of Spanish as it was spoken at that time (e.g. lacking usted/ustedes; the range of sibilants – not just s and ch but also ts, sh, z, zh; a lot more word-initial f), along with some Hebrew influences.
What impressed me is how easily understandable this video is to me even as a non-native speaker (although knowing a little Catalan and Portuguese perhaps also helps!). I can hear differences from the Spanish I know, sure, but I still understand, with the words I don’t recognise being guessable from the context. If you speak Spanish – or even Portuguese – you might find it interesting to give it a listen and see what you notice.