Creativity has (at least) two different meanings in literary criticism. One is like the creative in "creative accounting" where the creative urge is to make up crap about the text or to invent the most fanciful interpretation. A deeper creativity is the creativity of seeing what's actually there and asking the tough questions about it. Why is something one way and not another. How do we account for something that is (seemingly) anomalous.
Something that seems off, strange, is a good place to start. For example, I wondered why Juan Ramón Jiménez had created an anthology of his work that printed all his free-verse poems as prose, suppressing the original lineation. That seemed odd to me, because skill in verse is defined by, well, verse, and readers don't tend to read blocks of prose for rhythm. That question became the basis of a fairly original book chapter which should form part of my next book. What are the implications of this decision? How is this similar to what other poets have done?
If you are deeply engaged in a field, you will constantly be constantly confronted with things that seem off. Why can Donne be perfectly metrical when he wants to be, yet write the strangest lines elsewhere? If Greek and Roman poetry doesn't rhyme, why is rhyme so central to any neo-classical aesthetic? If you see the strangeness of what's before your eyes, you won't have a need to look for originality in spurious ways. A good critical insight has to be paradoxical, against the doxa or somehow internally contradictory in an interesting way.
Plodding, dutiful criticism just seems to go through the text and point out obvious things we already now.