How would a student justify inferring that “indigenous” means “originating in a particular region”?

The way in which a student could justify inferring that "indigenous" means "originating in a particular region" is by explaining what the origin of the word is. "in+gen" comes from Latin and means "to originate" (like generate). The suffix "-ous," on the other hand, is used in English to transform a word into an adjective, and it has the meaning of "possessing the quality of."

constantly changes their schedule.

always on phone a lot more than normal.