Are reasonable because jeans is plural. "is" is used when there is a singular subject and "are" is used when there is a plural subject.
Arachne is a weaver that boasts she is the best weaver in the universe and that no one can match her skills. This comes back to bite her later when she is put in a cloth making competition with Athena. Arachne, of course, loses and is turned into a spider.
Arachne's characterization foreshadows her fate by her being boastful.
