All I plan on doing on it is chat rooms (I like talking to strangers sometimes randomly), watching download movies only (never any streaming or anything), probably reading the occasional free comic book and that’s probably literally it. So how old, crappy and cheap can i go if I’m only doing these 3 things?
Honestly any MacBook with SSD will do the job.
You can get a 2015 MacBook Pro Retina, they come with a retina display which is way better than any other new Windows laptop screen, SSD which helps you navigate very fast, 8GB RAM standard which should be enough, a very reliable scissor keyboard (not the butterfly of models from 2016-2019). And also the trackpad has haptic feedback which makes it super useful and most of the time you wont need a mouse to use the laptop.
These go for about 150-250 on eBay. (At this price, no new laptop is gonna be better)