- Always capitalize the first words of sentences.
- Always capitalize the word I. - Can asks about ability. May asks for permission.
- We're not all guys.
That's a good question for you to Google or look into at the library. The British Isles have been settled by many people over the centuries, so English is a mash-up of many languages. There are elements of Germanic languages (including Old English), French, Latin, Greek, and more.