So I take it since the hover-hints also suggest "him" and "her" (ona) that this serves not only for the nominative (mianownik?) but also for either the accusative (biernik?) or dative (celownik?). Is that dual-use correct, that on/ona are NOT only used in the nominative (like he/she are only used that way in English and have him/her for the others?)
Him = Jemu
I gave him an apple = Dałam/dałem jemu habłko
Her = Jej
I gave her an apple = Dałam jej jabłko.
On & jemu are not in the same tence.
You can ask "who? what?" (kto? co?) for nominative and the answer will be "on". And there are questions for every tence (search for it, it is very helpful).
Wikipedia might help you a little. Also, don't worry, cause sometimes even Poles have problems with tences :) (https://en.m.wikipedia.org/wiki/Polish_grammar)
On- he ,ona-she,to-it ,one-they(only girls),oni-they-(only boys or girl and boy)
I think "it" is actually "ono", and "to" is "this". But I'm not sure--maybe the usage of "to" is closer to the usage of "it".
You are closer, but like everything in polish its not always simple. Usually "to" you might use like "to auto" -"this car"; and "ono" like "ono (dziecko) płacze" - "it (baby) is crying".
wait..if ona is she..and on is he..is the 'a' in "ona" supposed to separate it from "he"?
I think that's too far. We could then say that you have "she" and "he" in English so 's' separates those words. They're just similar, which I believe is quite common throughout different languages.