Jiang Chen highly valued Cai Zhaoji because in the Prehistoric World, connections and background were of utmost importance.
In the Prehistoric World, innate aptitudes didn't matter much; instead, what mattered were opportunities and Fate. As long as one's Fate was good enough, even a pig could start its own sect.
For a person, as long as you could forge connections with Great Divine Transcendents, no matter what your origins or status, it didn't matter. Eventually, at the very least, such a person would become an Innate Dao Sovereign.
Connections and background prevailed above all else. This was the reality of the Prehistoric World; only those with connections could reach the end, standing at the pinnacle of Heaven and Earth.
Without connections, no matter how unrivaled the talent or extraordinary the aptitude, it was tough to achieve great things; becoming an immortal was even harder.