Comments by "Traveller" (@traveller23e) on "From Zero to Hydrogen: The Future of Clean Energy Flight." video.

The other factor is that the designer of the Hindenburg wanted to use helium, but because the US had a virtual monopoly on that and wasn't trading it into Germany nowhere near enough could be obtained. Then his second plan was to use a helium outer layer with hydrogen inside, but even that was deemed impossible hence going with pure hydrogen at the end. It was certainly known at the time that hydrogen was a lot more dangerous, but the safer alternative just wasn't an option.
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Jet fuel does at least to some extent have the same issue as it's light enough, which is why aircraft wings these days are filled with an inert gas as the fuel is used up. I believe Mentour has a video explaining an accident caused in part by the fact that at the time they filled the tanks with air instead.
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