Given the movies diverged from the books a lot and also were a train wreck that managed to stay on the rails...
Radagast saved Middle Earth from an early disaster. He spotted the deterioration of nature long before anyone else, found the Necromancer and convinced Gandalf to look further, pulled Gandalf out from the middle of all out hellfire...probably more I can't recall.
So yeah, kind of like Jack.
My favourite part of the film.
I'm Indigenous Canadian and as young boy I remember heading out to one of my distant family's hunt camps on James Bay coast in northern Ontario one year. We drove out on snowmachines in the early spring and went from camp to camp to get to where we were going. Met so many people it was great. At one camp, it was an earth hut that was old and ancient, built right into the swamp and froze every year. It was so low to the ground that in the winter time it was completely covered in snow and ice just next to the treeline of open tundra. A path led down to the entrance and inside it looked like something from Middle Earth with a little camp stove and light flickering out from holes in the stove. A bit of candle light but it was dark everywhere with only one tiny opening to the sunlight creating a pillar of light in the middle of the room. Smoky from the fire, steamy from the dampness inside, a low ceiling and everything old, tattered, dusty and dirty.
The owner of this camp was an old Cree trapper that looked like Radagast, complete with an old fur skin hat that was as old as he was all twisted and flopping randomly in different directions. An old wrinkled brown face, long greying unkempt hair and a thin beard. He had bright grey eyes and he was completely eccentric and funny. The only thing missing from his camp was a sled pulled by giant rabbits.