Although Bilbo Baggins is a diminutive hobbit, he may be the most human-scaled character in all of J.R.R. Tolkien’s Middle-earth fantasy world. He is a quiet sort who enjoys nothing more than a nice cup of tea by his snug hearth. No adventurer, he’s dismayed in Tolkien’s novel when the wizard Gandalf and a cadre of dwarves recruit him for a battle with a seemingly invincible dragon.

Still, for an actor to play the timid Bilbo takes some nerve. Millions of Tolkien readers have their own image of “The Hobbit’s” protagonist. Stepping into his oversized footprints is not a casual lark. Little wonder, then, that Peter Jackson wanted Martin Freeman to star in his “Hobbit” trilogy, which launches worldwide this week with “The Hobbit: An Unexpected Journey.”

In a phone conversation last week, Freeman said he didn’t feel he was sticking his head in a dragon’s mouth by taking on the iconic Bilbo.

Q. How would you describe the young Bilbo, who is a much older character in “Lord of the Rings”?

He’s not particularly bold. He’s not the main guy in the room. He’s not an alpha male. There’s a timidity to him which is part of his pomposity as well, as we join him at the beginning of the show. In many ways he wouldn’t say boo to a goose. But he’s quite pent up and I guess that comes out extraneously through his fidgeting.

Q. Did donning Bilbo’s large feet affect your performance?

The feet were key. If your feet are 6 inches longer, then your gait changes. Your balance, your equilibrium, everything changes. Those things don’t have to be a conscious decision. But they do add to it.

Q. Does it really feel like entering a fantasy realm to perform in a Peter Jackson mega-production?

You’re aware that you’re entering a magical realm. On the other hand, it’s highly practical, highly pragmatic and very unromantic. The magic and all that is what the audience sees. What you see day to day is going to work. Albeit very pleasurable work. You’re still making a movie, which is graft, you know?

Q. Does it require more imagination to act opposite computer-generated characters like Gollum?

Yeah, given I’ve never seen a warg (big bad wolf-hounds with a taste for hobbit flesh), let alone killed one, that does require a lot of imagination. It’s a leap of faith between you, the director, the digital people, everything, to kind of construe exactly what it is I’ve got my sword embedded in. It does call a lot on the imagination. I found I really enjoyed that. After all, we’re people who do for a living what we all do when we are 5. Haven’t grown out of it.

Q. There are many newcomers to the story in the cast, but also many actors who had lived in their parts for years in the original “Rings” trilogy. Did that feed helpfully into your performances together?

It helped me working with Gollum, the first stuff I was doing. It helped that Andy (Serkis, whose on-set performance was data-captured to create the creature) was so adept in that character. To be nose-to-nose with Gollum, on the receiving end of his threats and his malice and his madness, really helped me in finding how Bilbo reacted in life-and-death situations. And with Ian (McKellen) as well, as Gandalf. You feel you’re working with this solid base. And also you’re in Pete’s hands. He knows what he’s doing. He knows what he’s doing in Middle-earth. That gives you the freedom to skip around and find things and play.