Actually Harley, i started with the Hamilton soundtrack. I just listened to it one day while driving around doing errands. It was SOOOOO engaging, that I immediately wanted to see the show. And you get 90% of the story JUST from listening to the music, IMHO. BUT, If you want just one song, then start with the opening number “Alexander Hamilton”.
Even better, you could watch this: https://www.youtube.com/watch?v=WNFf7nMIGnE
Lin Manuel Miranda performed at the Obama White House Poetry Jam. He was going to perform something else, but at the last minute he decided to perform this piece he’d written about Alexander Hamilton, inspired by a biography he’d just read on vacation by Ron Chernow. It’s an early version of the opening number for the final musical. It was so well received and lauded that he decided to expand it into the musical that we know now.