The only thing TFA lacks that the PT has is George’s wild imagination and world building skills. But as far as telling a competent story with likable/layered characters Lucas didn’t showcase any of the talent he once had when making the OT.
I think you have nailed why the PT is not as good as the OT. But I think that GL’s imagination is more important to the overall story than his ability to write characters which is why even though TFA has better character stories, I think it is a weaker film because the overall plot is unimaginative.