How was John the Baptist able to baptise Jesus before Christianity was created and Jewish people did not use baptism?

Jewish people did not use the term "baptism", but they did use cleaning with water to serve as a spiritual cleaning of the body before entering the presence of the Lord. Ceremonial cleaning of the feet and dishes is written into the law. John the Baptist was encouraging Jews to repent from wrongdoing and getting washed as a sign of a change of heart. For Christians at the basic level baptism is also a cleaning away of the past and having a change of heart which is similar to the spirit of what John was preaching. Of course, the very big difference is the change of heart for the Christians is to accept Jesus as their savior.

https://en.wikipedia.org/wiki/History_of_baptism