"Copyright" refers to the legal status of an individual or entity who owns the exclusive rights to a creative work, allowing them to control how that work is used and distributed.
Instagram does not copyright your photos. You own 100% of your Instagram photos. Instagram's TOS state, "we do not claim ownership of any Content that you post on or through the Service." However, posting a photo on Instagram grants Instagram a non-exclusive, transferable, sub-licensable, royalty-free license. This license allows Instagram to use your photo in its advertising, marketing, and promotions and let other users share it. By deleting the photo from Instagram, you can revoke this license. Be aware that posting a photo with copyrighted content, such as a song or image, may violate the owner's copyright. Before posting copyrighted content on Instagram, get permission.