Cool Video - Origins of Consciousness
There may not be a universal definition of consciousness, but it definitely has something to do with an awareness of existence - usually an awareness of (at least) one's self. Add awareness of surroundings, of the the passage of time, the abstract idea of things or situations that do not yet exist in the future, cause and effect and consequences and rewards and ramifications and pretty soon you have layers of intelligence and sophisticated abilities that everyone would agree qualifies as consciousness... or would they?
Many believe God was once alone in an empty universe before having created it. Except for "Self" the things mentioned above didn't exist in that scenario - there were no surroundings or time or consequences - yet few would argue such a Creator would not have been conscious. At the other end of the spectrum we can program a robot with AI to process all these concepts and manipulate its environment to achieve its goals but - would it be conscious?
This video by Kurzgesagt (which I found here at SelfAwarePatterns) explores these gray areas and at least suggests a process that leads to consciousness - even if there is no one critical threshold.
https://www.youtube.com/watch?v=H6u0VBqNBQ8