Actually, that's fine. There is a type of climbing called "bouldering" which is exclusively with short walls. Most, if not all, rock climbing gyms should have these because they are so much cheaper to create. You don't even need a harness because you're not high enough to hurt yourself if you fall; so you can save the cost of harness rental too!  Bouldering isn't easy just because the walls are short. It often includes a full range of difficulties, so even experienced climbers can practice particular skills conveniently.