If you still have the length of filament you cut off, you can verify your temperature theory pretty easily by loading it up temporarily and trying increasing nozzle temperatures until you get it to extrude. That spool of filament may have been contaminated by having a couple of pellets of the wrong stuff in it. Plain PET (rather than PETG) is most likely, I think, and that stuff won’t extrude until you wind your nozzle up to probably about 240° C.

It might have been a diameter issue as well, but I’d doubt it. My printer’s drive gears can still grab objects that are quite a bit smaller than the prescribed 1.75mm filament diameter, and if the stuff were so thin or thick it wouldn’t feed I think it’d be quite obvious to the naked eye. I imagine this is the case with pretty much any modern printer.