There are animals like cats, horses, and dogs, even Villagers that you can tame, or as I like to say “Hire” with cooked meat to protect you. As for dragons though, Mesecraft is still in development and there are lots of things that need to be done, as there really are only two guys who work on Mesecraft. SO while dragons would be cool, they are still being considered as they are a very destructive mob and we already have problems such as massive accidental Boomer “Those tnt guys) explosions that set of devastating forest fires, so if a small mob like a Boomer can do things like that, imagine what a dragon of great size can do.
However if you really want things like dragons, there is a server called “Centeria Survival Deluxe.” While it is not the official server, it’s kinda a testing ground for what COULD be added to Mesecraft in the future.