There are waaay too many important songs in history to count here. From the minstrel show, through the creation of jazz, blues, country, R&B, Rock and Roll, Rock, Heavy Metal, Punk, Rap, Hip Hop, and Alternative... there are too many songs in history that had a great effect on the world. I don't have a song but I do have an artist that I think had one of the greatest effects on music and history today. If I recall my music course lectures, there was a man named Scott Joplin (I'm going on pure memory so if you have anything I may have forgotten, post it!) who introduced a new type of music to the people at the 1893 World's Fair in Chicago. While not new for some, this new brand of music was called ragtime and it is essentially the grand predecessor to all of the music genres (post-Renaissance, classical and opera do not count) we know today, most notably jazz and blues.