That's a common explanation but the article links to a study that supports another explanation, capsaicin having likely evolved for its antimicrobial properties instead:
Evolution just works on chance mutations and capsaicin is just what chilli peppers happened to start producing. Maybe if they happened to make penicillin instead they'd be better off, but they just do with what they have and that is capsaicin. They were just lucky that birds and humans tolerate capsaicin.
> Humans don't like chilli pepper.
And now you write:
> No other animal other than humans like chilli.
Which one is it?
Also, there are different species, I've eaten lots of different chili, I've eaten whole raw Bhut Jolokias, that was not pleasant, I didn't like it, it hurt a lot and the taste was not nice either. Lots of milder species are lovely to eat raw, they have a mild burn which I do find enjoyable, and they have a fresh sweet flavor which tastes great.
None. Both statements are false. Chili Pepper have a few pests as any other crop has. Pepper weevil for example.
I "like" a thing when I get pleasure out of practicing/consuming it in some form.