What term describes something ordinary, dull, or routine?

The term "humdrum" specifically captures the essence of being ordinary, dull, or routine. It conveys a sense of monotony and lack of excitement, which aligns perfectly with the concept of something that is unremarkable or average. In contrast, the other terms present a much different connotation. "Exciting" suggests something thrilling or stimulating, while "extraordinary" denotes something remarkably unusual or exceptional, far from being mundane. "Novel," on the other hand, refers to something new or original, which also stands in opposition to the idea of dullness or routine. Therefore, "humdrum" is the term that accurately reflects the ordinary nature described in the question.