Classic Buddhism describes three or four stages of enlightenment depending on the tradition. Theravada recognizes four, Mahayana three. If you are looking for any kind of rigor in the literature, you’re looking in the wrong place for the wrong thing.
Dr David R. Hawkins created a scale of human consciousness, with a progression from 1 to 1000. Anything over 700 is enlightenment, with level 1000 being the level of Jesus and the Buddha. He taught that more than 1000 could not be contained in a human vessel.
When I did my own explorations into the nature of consciousness, I was struck by just how much of it was remaining unexpressed. The remainder of a person’s consciousness that doesn’t express through the being resides with the so-called Higher Self. This Higher Self is a person’s direct connection with the divine.
Identification as the Higher Self is the point of spirituality. The Higher Self is aware of things that the lesser self can never directly apprehend and is there with you to help you learn how to grow into a being that can utilize divine perception.
There are two aspects to spiritual growth, perceptive responsiveness and level of surrender. You level of surrender determines how much divine energy flows through you while your level of perceptive responsiveness determines how well you are able to understand and use it. When you are most perceptive, you are least in possession of surrender and vice versa, they tend to be conserved between them.
A high level of surrender is generally how people define enlightenment. Personally, I think one needs to develop both capacities.
The universe is endless and offers countless wonders to experience, understand, and use. To say the journey could ever end, is just really silly to me.