You asked us if it's true that elephants can't jump, and yes, it's true. Adult elephants just aren't built to jump because they often weigh 16,000 or more pounds. They're just too heavy to make the leap.
Not only do they not jump, elephants never get all four feet off the ground at once, and that is even when they are charging at full speed. So, technically, I guess, elephants don't actually run, they power walk.
And why should they jump? The great leapers of the animal kingdom often evolved that skill as a way of avoiding predators, but nothing in an elephant's environment, at least in their recent evolutionary past, required them to hop around.
So, despite what you may have heard, believe me when I say, elephants are earthbound.