What makes Blake's poetry so innovative?

his engravings

his knowledge of animals

the thematic characters he uses

the number of metaphors he uses

(A.) his engravings

For most part of his life William Blake was not recognized as the great artist he is considered today, and it was mainly because of the lack of technology to print his engravings. He is considered as the Complete British Artist, he was a poet, a painter and an engraver, so his work needed to be seen from three angles to be fully understood.

The answer to this question is his engravings.