Jellyfish are cnidarians, a phylum which also includes corals and sea anemones. Jellyfish are a specific lifecycle stage of medusozoans (their own subphylum), while corals and sea anemones are anthozoans (another subphylum of Cnidaria).
So yup, they are polyps before sexual maturity. And you’ll find they’re more closely related to corals than they are to members of any other phylum.
Edit: I highly recommend that anyone who wants to get lost in the world of marine invertebrates check out WoRMS and then follow along in parallel on Wikipedia as you navigate the tree.
An infinite amount of monkeys each given an infinite amount of time would produce all infinite strings possible on a typewriter (this includes ones that just happen to be terminated with a neverending substring of blank spaces, i.e. one where the monkey stops or presses whitespace keys and nothing else an arbitrary number of times).
If a cure for cancer exists and is expressable through language, they would not only produce one, but it would be there in every single language transliteratable to a Latin script; it would be there in ASCII art; it would be there in literally every text-based form imaginable. Of course the trouble would be sorting the infinite wheat from the infinite chaff.
Edit: https://libraryofbabel.info/ for the finite strings of 3200 characters.