You don't need to be a talented artist tocreate a manga. But you do need to know the steps it takes to attract readers. Case example: One piece and Shin Chan. One piece art is not in anyway superb or anything and their whacky anatomy is completely....well.... whack. But they offer solid and interesting storyline and lots of climaxs to keep reader entertain and continue reading. Shin Chan is definitely not artistically drawn. But its humour is very good.

A good art is a plus. But it is the content that matter. Perhaps you could try looking at an anime/manga series called "Bakuman" to understand few ideas about how to be mangaka.