It's an animation blog. With context it's obvious the blog is going to discuss the "Rudolph" animation, not the song, since the latter has no place on such a blog.

Who knows how far back the chain of inspiration and influence goes, but Robert Lewis May’s book predates Gene Autry [1]. The wiki link you shared actually mentions the inspiration for Gene was a children’s book.

[1] https://home.dartmouth.edu/news/2011/12/rudolph-red-nosed-re...

>The wiki link you shared actually mentions the inspiration for Gene was a children's book.

And even mentions May, specifically:

>In 1939, Marks' brother-in-law, Robert L. May, created the character Rudolph as an assignment for Montgomery Ward, and Marks decided to adapt the story of Rudolph into a song.

Johnny Marks (who worked on the stop-motion show) was credited with writing the Autry song (and his brother-in-law created the character itself).