Why does the French language sound so different from Spanish (and other neighboring languages)?

I’m not sure. I think US-Mex border-zone Spanglish is more of a sociolect (most speakers also speak standard Spanish and/or English, and use Spanglish in particular settings), while Portuñol is more of a true “language,” with people who use it more or less exclusively – but the difference is probably one of emphasis, with Portuñol also having some sociolexical aspects, and Spanglish also having some “true language” aspects.

This is important. There was much more of a language continuum across France and into Spain until relatively late standardization in the 20th century. Graham Robb discusses this in* The Discovery of France.* It’s not the best source for this topic, but the only one I’ve read recently enough to remember the title.

Supposedly you could go from the Strait of Gibraltar on the west to the Strait of Messina in the east, along the Mediterranean coastline, and in every locality along the way they can understand the dialect of the next villages on either side of them. Regardless of the official name of the language at any point along that itinerary. And yet people from Andalusia, on one end, and Calabria, on the other end, cannot understand people from Montpellier in the middle all that well—let alone each other. That is a dialect continuum.

I’ve heard that claim, but could it be due to bilingualisms rather than a true continuum?

BTW, I spent time in Barcelona and always spoke French when I was there. Many were very conversant, others could understand me, but one oldish woman in the Barcelona market left me confused: “Yo no hablo español.” Could she have known so little Spanish that she thought I was trying to speak Spanish? Was it just a polite way to tell me that I was speaking no comprehensible language?

Was there absolutely no trace of the Vandal language when they were overthrown by the Muslims? The Reconquista replaced a Germanic language with a Romance language, apparently?

The Vandals were first defeated in Iberia by the Visigoth, and were pushed into North Africa, around 500. By the end of the 7th century the Visigoth had adopted Latin language and religion. There may have been some Gothic language speakers left in the 8th century but no later. The Reconquista didn’t really replace any language since the Latin speakers kept their culture throughout the Islamic rule (which only lasted a few years in some places).

I’ll pile on. I’ve had formal language training in Portuguese, French and Spanish and agree that Portuguese sounds very little like either of the other two. There are some similarities because of the romance roots, of course, but of the three, Portuguese was the more difficult for me to learn. The only resemblance to French is the nasality in vowel pronunciation. I always thought of Portuguese as Spanish that’s been edited with a meat cleaver. Bom dia!

Some dialects of Spanish do have the ‘zh’ sound (Argentinian Spanish, for example).

If the shows you are watching simply show ordinary French people speaking that language as they go about their business, I’m surprised you can sustain the notion that it seems artistic or snobbish. As with “guttural” German, that idea is more or less a caricature-like imagined phenomenon.

It’s certainly not a misperception when comparing French and German, as the two languages are about as different as two Indo-European languages can be, notwithstanding a few early borrowed words that today still betray their common origin–e.g. French fenêtre and German Fenster which both mean “window”. I don’t remember offhand which language borrowed from which.