The photos were square, and there were filters. Those features made things look cute. Also getting a photo from your phone camera lens to the internet was ofte

The photos were square, and there were filters. Those features made things look cute. Also getting a photo from your phone camera lens to the internet was often a multi-step process at that time. Instagram was two clicks and on your feed. And the sharing model (all photos pushed to every follower) made people try a little harder on the images. That made it popular among amateur photographers. The profile model (grid of photos) also encouraged some level of vanity. People discovered it by being invited by friends who like cataloging pretty things.