Well, the whole point is...
In a convo i saw earlier that was removed from M1, it says there were 5/6 before Neo that Mopheus thought were 'The One'. All ended up believing what Morpheus said about being Ones and all fought and diedat the hands of an agent. So to answer your question, i believe Mprpheus was just clutching st straws until he found the one h was looking for.
MC> This is called obsession.
Obviously Morpheus would have been searching through the matrix code for code that was unstable and opposing to the reality of the Matrix. When he found Neo, he found out that his rejection of the world of the Matrix was much higher than the others he had found. And he contacted him! 🙂