I can't imagine what it must have been like for people to hear about yet another "miracle drug" that cures most diseases – and then gradually realize that this one actually works.

take the word "disease" out...

and you CAN imagine it : Viagra

Ha, true! I forgot that used to not be a thing, and people were trying everything from crushed beetles to insanely hot chili peppers to crazy dangerous poisons, and still nothing really worked.

It wasn't. "Stuff that kills bacteria" has been known for a long time, including times when nobody knew what bacteria were. Not every dirty wound was fatal, there's mixes of plants, applied to wounds, that do a good job.

Penicillin was the first highly effective AND mass producible antibiotic, though.

While true, actually applying it in practice took a long time. Imagine the shock and horror when male doctors were told by midwives that washing hands and keeping things clean reduced infant mortality.

There is "antibiotics" already

I wonder why people downvote... GP said "Penicillin" as an addition to a list which had already "antibiotics" in it.