Is it still worth studying French at school?

It depends on what you want to do afterwards, right? School French only makes sense if you actually plan to use it. If your school forces you to study it because "it's culturally important", fine, but it'll still be pretty sterile learning. French grammar is genuinely boring, and learning irregular verbs without ever talking to anyone is like reading a video game manual without actually playing - it's pointless.

That said, if you're thinking of going abroad, working in certain fields (diplomacy, tourism, research), or just traveling to France or French-speaking Africa, then yeah, it's worth it. But you have to add something living to it yourself: watch films, listen to music, talk to someone online. School French on its own is a dead base. If school is your only option and you're not that interested anyway, just get the grade and move on - it's not a language that'll change your life if you don't actively use it afterwards.