Don’t worry, Henri will catch on someday. My lovely Pringles was a jumper from the start, as long as there was a rug to launch from, she could pretty well make it. The good part about that is if I don’t want her somewhere I move the rugs so she can’t get a good takeoff from the wood floors.
My foster, Toby, and Daisy both came from situations where they had spent their lives in little cages and it took weeks for them to even move outside of those dimensions they grew up with, even though they had lots of room now. They didn’t even know they could stretch their legs and run, the first time they discovered that was a hoot to watch! Toby will startle into a sprint and stop, sit up and look around like “wow!”.
For Toby and Daisy I had to start out stacking the couch cushions on the floor so they could learn to navigate up. In the condo, Pringles will bounce from floor to floor, but Daisy likes to cautiously hop onto the boxes I put as a halfway step for her.
Maybe you could coax Henri onto low things with treats so he gets the idea. Or borrow one of my cats, I think Pringles learned her leaping from them.