Far Cry 5 is a beautiful game about fighting a religious cult, petting dogs, and blowing things up. Far Cry 2 is a beautiful game about fighting mercenaries in Africa, running with gazelles, and blowing things up. Ten years set the games apart, but in many ways, Far Cry 2's attention to detail is more impressive than Far Cry 5.
As a new video from YouTuber Crowbcat (who did something similar with Grand Theft Auto IV and V) shows, some things that Far Cry 2 does that Far Cry 5 does not include: shooting through cover, taking out individual tree limbs to expose bad guys, and fighting against sophisticated AI that can carry wounded allies to safety.
Obviously, there are many things that Far Cry 5 does better. It looks much better, it has way more variety in terms of what you can do in the game, and though it doesn't really succeed, it does try to tell a more involved story.
Still, it's interesting to see what the developers' priorities were 10 years ago.