more 这里是副词吗?

1 yes,it is indeed an adverb here.（见韦氏字典词条,作为副词的第二个功能就是和非单音节形容词或副词组成比较级）
more
Function:
adverb
Date:
before 12th century
1 a:in addition b:moreover
2:to a greater or higher degree —often used with an adjective or adverb to form the comparative
2 more than/ no more than中,more 是形容词