This is the 6470th most frequent Japanese word.
ズブ
"ズブ" (zubu) is a casual term meaning "soaked" or "completely drenched."
Here, 'ズブ' is part of 'ズブズブ', an onomatopoeic expression used to describe the state of being thoroughly soaked or saturated.
彼はズブズブ濡れていた。
He was soaking wet.
In this context, 'ズブの' is used to describe an absolute state, often combined with words like '素人' (novice) to indicate someone who has no experience or knowledge in something.
彼女はスポーツにズブの素人だ。
She is a complete novice at sports.
'ズブズブと' in this sentence is depicting a slow sinking or immersion, often conveying the action of being caught or deeply involved in something.