Bitcoin is not a first cryptocurrency has ever been created, there are other cryptocurrencies were developed before Bitcoin. These cryptocurrencies did not get good adoption and success like Bitcoin but they paved paths to success for Bitcoin.

You can learn about Bitcoin prehistory with some resources.
Bitcoin and cryptocurrency technology. It's a draft of Princeton book, available for download.
More information about the book, authors
Buy it on Amazon
A download link to official version of this book, is available given by Maus0728 at https://drive.google.com/file/d/1LGb3JT5R_xpm8Je2jzKkbFJYIE83RFzv/view

There is another source on Bitcoin prehistory.
Saylor.or Academy's course: PRDV151: Bitcoin for Everybody.