Yeah I never heard about them being usrd to signify pauses in speech. I’m not a native speaker but I think in general they are used to separate “sentences” (they have a verb and all that shit), interleaving sentences, and lists of items. Ofc there is a lot of nuance, for example, this sentence, and there are cases when commas should be left out (afaik). In my language I would always put a comma before “but” or “because” but in English it seems the words themselves separate the sentences. Anyway, shit is weird, English is very random.