Complex sentence: Often, existing programs would be launching ground for new cartoon characters-in 1956, the Howdy Doody show aired the first "Gumby" clay animated cartoon from creator Art Clokey.
Split into simpler sentences: Often, existing programs would be a launching ground for new cartoon characters. In 1956, the "Howdy Doody" show aired the first "Gumby" clay animated cartoon from creator Art Clokey.