Pokemon wasn't a manga first. It started as a game and then branched out into different areas like anime and manga. The game was the initial point of the Pokemon franchise.
It's not straightforward to say who made the first manga. The concept evolved gradually, with many influences and contributors along the way. Different works from various artists combined to shape the manga we know today.
The first manga is believed to have originated in the late 19th century. But pinpointing an exact date is quite challenging as the concept evolved gradually over time.
Figuring out the first shonen manga isn't straightforward. 'Kamen Rider' was also among the early entries in this genre, influencing subsequent works with its unique storylines and characters.