I have heard that at least some of the people who animated Snow White at Disney immediately did some porn of her when they were done. Not for posting, of course.
My father had a photocopied drawing of the Coyote and Roadrunner having sex well before the Internet was really a thing. I’d say that there’s been that sort of porn as long as animated shows have been around; the Internet just made it more accessible and widespread.
Yes, especially thanks to the Resident Evil series.
The Fella and I had a google-off one night for a rule 34 thing. (This was years ago.)
I picked (out of nowhere) ‘farting porn’. Yeah. It exists.
I got a response quicker and won. It was a pay site and just the descriptions made us crack up.