The way I see it, “little Ani” has three important moments (that come to mind right now, I’m sure there’s other smaller moments) that present him as more than just a happy-go-lucky kid: the “I’m a person” outburst, his forlorn look aboard Padmé’s ship, when he and Padmé comfort each other in a way, and his test at the hands of the Jedi council (he looks definitely vulnerable, yet he snaps back at them “what does that have to do with anything”). In all instances he shows vulnerability, loneliness and a strong temper... That, to me, is enough to present a more rounded-out, complex character than just the happy kid you percieve.
Anakin was out in space for the first time, and without his mother; of course he's going to feel lonely. That just makes him a normal child. And his little temper flare with the Jedi Council was also similarly typical of any child; kids even throw tantrums over next to nothing. These instances don't add any complexity to Anakin's character at all. They just re-affirm that he's a typical kid; seemingly unaffected by the gravity of circumstances he was born into and grew up with. He merely reacts to what is happening in the moment.
I ask you to recall portrayals of actual complex children in movies. Be it "Stand By Me," or "The Sixth Sense" (which came out the same year as TPM), or "The Professional" (ironic, isn't it?); those child characters didn't just benefit from good/great acting, they were visualized (by the creators/writers) to be complex, nuanced, and mature beyond their years. Had Anakin been portrayed that way in TPM, it would've laid a better foundation for his climactic turn.
Actually, sometimes a single line of dialogue does define a character, though I’ve presented two more instances… Besides, isn’t enslavement in itself, as well as the entire situation Anakin is thrust in during TPM as a little, unprepared kid (leaving his mother behind, feeling the rejection of the council) enough to leave a lasting mark on any person and influence their later development?
If you just take out the few bits of dialogue about slavery, and you showed Anakin's TPM scenes to anyone who didn't know anything about these films, I doubt that you'd get many people to suggest that Anakin's characterization had anything to do with enslavement, or that it had any real depth at all. He's portrayed as a happy kid; he's enthusiastic, kind, loving, good at everything, comfortable around strangers, sure of himself, and generally well-adjusted. And that was all intentional.
But, since I'm clearly not convincing you of how Anakin was intended to be portrayed in TPM, perhaps George Lucas himself can make this clearer. This excerpt is from a "Rolling Stone" interview with Lucas that was published in June 2005:
Well, a lot of people got very upset, saying he should’ve been this little demon kid. But the story is not about a guy who was born a monster – it’s about a good boy who was loving and had exceptional powers, but how that eventually corrupted him and how he confused possessive love with compassionate love. That happens in Episode II: Regardless of how his mother died, Jedis are not supposed to take vengeance. And that’s why they say he was too old to be a Jedi, because he made his emotional connections. His undoing is that he loveth too much.
"His undoing is that he loveth too much." That's the level of complexity that George had in mind for Anakin in the PT: he was too old to start Jedi training because he'd already learned to form attachments. That statement leaves no ambiguity about this character's portrayal, or what Lucas was aiming for. GL wanted a sweet young kid in TPM who we would feel sorry for. That's about it. He then gave him a turning point in AOTC when he couldn't save his mom. And his fear of that same fate happening with Padme led to his downfall.
Well, there you go, to me, Anakin’s arc was well crafted though sometimes not executed so well…
There's nothing about Anakin's upbringing in slavery, or his experiences as a Jedi knight, or his complexity of character that the PT was ever meant to convey as the reason why he became Darth Vader. He turned into Darth Vader because "he loveth too much." That's straight from the creator's mouth. And that's what disappoints me most about the prequels. Not the bad acting and horrible dialogue; not the effects; not even the stupidity and goofiness. It's the story; it's the rationalization for Anakin's turn to the dark side that I find ill-conceived, poorly-established, and too incongruous with Vader of the OT.
Had the young Anakin in TPM been shown to be resentful of the powerlessness of his enslavement, or jaded by it in some demonstrable way, then his turn later would actually have more of a foundational basis. TPM would've been worthwhile. If a true complexity had been intended, and executed well on screen, it would've made more sense. Instead, Lucas went out of his way to portray a joyful and innocent kid because he wanted Anakin's later loss (his mom) to create fear (of it happening to Padme). In TPM, *fear* is the only thing about Anakin that was established to predicate his eventual turn . . . because "he loveth too much."