Is shuttle a proper noun

No, the noun 'shuttle' is a common noun; a general Word for any transportation that travels regularly between two places; a general Word for a device used in weaving.

A proper noun is the name or title of a specific person, place, or thing; for example, SuperShuttle (airport transportation service) headquartered in Scottsdale, AZ or the Space Shuttle Atlantis.

The Word 'shuttle' is also a verb: shuttle, shuttles, shuttling, shuttled.