Jet fuel is way less flammable than hydrogen or even gasoline. Hydrogen is among the most flammable substances, whereas jet fuel is really hard to ignite unless aerosolized. https://www.youtube.com/watch?v=7nL10C7FSbE
The other issue with lighter than air flight is that you can’t go very fast (the Hindenburg had a top speed of 84 mph) because you have a big gas bag that creates drag so ground transportation starts to look like a reasonable alternative.
