Intelligent life does not mean more intelligent than humans but having intelligence in general.
Intelligence has been defined in many ways and there are many ways that it is exhibited in, which often makes a single test meant to measure intelligence irrelevant.
One of the general characteristics of intelligence is the ability to learn. An intelligent creature has the ability to learn while it tries to achieve its objectives and make changes in its actions to be able to accomplish it in a better way. For example, if an animal that is hurt while trying to reach its objective of obtaining food once and the next time does not perform the same steps but chooses an alternate way has intelligence.
The objectives for different intelligent organisms differ and they evolve as the intelligent creatures evolve. They could vary from just a basic objective of obtaining food and staying alive to more advanced objectives like those that humans have.