There is nothing insignificant in walking past someone.
A whole universe just strolled by, their anxiety caused by that test coming up, their worldview that differs from yours, their moments of joy pure adrenaline depression monotony, their troubles that may trump yours their Aunt with that terminal disease or the Dad that's never home, their mental to-do lists that grow and grow and grow, their images of reading on that comfy chair, their time spent by the bonfire, and their favorite quote that's always in their head.
But we just keep walking despite all there is to see, and we're thankful for the people that walk by our side, and share in our moments, our troubles, our images, our time.
I thought of this after walking past a stranger and thinking something along the lines of, "Wow, I know absolutely nothing about her. Her life could be crazy and interesting or super duper sad but I'll never know."