I don’t know of any time after we figured out what viruses are that we didn’t know they jumped species. I mean syphilis. We know exactly where it came from. Same with anthrax.
Most diseases don’t jump. But jumping does happen. Flus do it a lot because of how the flu works, it’s basically a bunch of related fast mutating illnesses that hit most mammals. Has always happened. Will always happen. And at no point have we not comprehended that. WE know. There’s no mystery here. Zoonosis and anthroponosis are not new concepts, and are very well understood and documented.
I will look into that. I’m willing to be wrong. Truthfully everything seems on its head lately. There are two theories on viruses (probably more) but I will revisit them, it’s been years since I have. Thank-you.