If the Church were depending on human beings to exist and stay unified how long do think she would have lasted? Probably about twenty minutes, max!
There are no governments or nations that have lasted 2000 years. Very little else in this world can claim such antiquity and even if it does can it claim to have remained essentially unchanged in its dogma or teaching?
The Catholic Church is one, even after 2000 years. An unbroken line of Popes back to Peter and an unbroken line of succession for all the Bishops back to the Apostles through the laying on of hands. Not bad. Our history is not without some pretty questionable moments, in terms of the human elements of the Church. That the gates of hell would never prevail against the Church certainly suggests they would try again and again. But here we are, a miracle. Still standing after all these years! Christ is true to his promise to remain with us all days unto the consummation of the world.
We, the human elements of the Church may not live teachings of Christ perfectly, but the Church has never failed to teach what Christ taught even (as now) when the world hated us for it. At times we are tepid and struggle to find our voice, but Christ still speaks and ministers even in our weakness. St. Paul once wrote regarding himself and his fellow clergy: But we hold this treasure in earthen vessels, that the surpassing power may be of God and not from us (2 Cor 4:7). When I think of the human weakness of the Church whether in the clergy or in the laity, I am absolutely struck by the truth that the continued existence of the Church all these centuries is a true miracle, right before our very eyes. Yes! A miracle.