I am wondering if there is a Ruby method call that shows only the methods defined by the Ruby object it's called from, as opposed to all the methods defined by its ancestor classes, which is what methods seems to do.
methods takes an optional boolean parameter, which specifies whether to also list the methods from the object's class and its superclasses or just the object's singleton methods. So you can do obj.methods(false) to only get the singleton methods defined on obj.
If you want the methods defined by the object's class, but not those defined by its superclasses, you can get that by calling instance_methods(false) on the object's class, so it's obj.class.instance_methods(false).