The Gumby theme song on the videos I have is different from this one. It looks like all the shows are from the 1967 series. It has the Indian Challenge episode I remember seeing on TV as a child.

Here's the song!

He was once a little green slab of clay. Gumby!
But you should see what Gumby can do today. Gumby!
He can walk into any book, with his pony pal Pokey too.
If you've got a heart then Gumby's a part of you.