It's very, very hard to get laid off / fired in France if you haven't done a major fuckup. It's possible, but the notice period is 3 months during which you're legally entitled to spend one or two working hours per day actually job hunting.

Unless you voluntarily quit, you get ~50% of your old salary for up to 18 months (unemployment benefits last for the same duration as your latest work contract, with an 18 month cap) as long as you can prove you're job searching. If you exceed the duration you get an insufficient, but non-zero, financial help of ~500€/month (which would cover a 2 bedroom rental in any small city and one bedroom in a mid-sized city, but not housing for a major city like Paris or Marseille).

Families get extra subsidies based on the number of children, and for long-term issues you can apply for subsidized housing, etc.

Also, healthcare is very cheap (and many emergency care things are free, as well as all prescription medicine), which means that if you can cover room and board you'll survive. You may have bad surprises but not "lifetime debt" bad surprises - that's why whereas the US financial planning advice is to have 3-6 months of living costs saved, the French advice is 1-3 months.