Why Did Someone Create The Radio?

Kind of the same reason we use mobile phones.  For communicating over distances.

The first people who discovered radio waves didn't have that in mind, of course.  They were just faffing about with magnets, electrical currents and finding out about the properties of electro-magnetic waves.  This was in the late 1800s and exciting things like how electricity might be used to light our homes were still being discovered.

The first big users of radio (or wireless telegraphy, as it was called then) were ships, for emergency communication. The sinking of the Titanic is a notable example, boats came to the ocean liner's rescue and people in New York knew about the disaster hours before any survivors got to shore, precisely because of radio communications.  It was also thought that radio comms would help boats know about hazards near shore or en route (not that these comms helped the Titanic, much).

There was also early interest in using radio instead of post (for mail comms). Radio technology making home-sets practical really developed during WW I.

Early broadcast efforts in 1919 were mostly meant as public information bulletins, with broadcasts of music and chat taking about 5 more years to evolve.

Radio waves had their first major users in the shipping industry.  They were used to issue warnings to ships about hazards, because they allowed communication over long distances.  Just like mobile phones are used today.

The radio that you buy and use in your house came about because

A) advances in technology made it feasible for ordinary people to afford one and have it in their homes, running on electricity or batteries, and

B) Because it was thought in 1919, post WW I, that public information broadcasts might be useful for people to listen to.  Prior to that buffoons had access to radio sets and were eagerly communicating with each other (just as they do today, on other frequencies), but Mrs. Jo Public probably wasn't  part of that scene.  The point of home radios was to give essential information to the masses quickly.

It took about 5 years for the possibilities of cultural broadcasting to be realised. And thus the BBC was born...