In New Moon, some symbols are very apparent while others hide deeper in the text – or maybe in more subjective interpretations – so bear with us. Descriptions of Jacob as "the sun," for example, run rampant throughout the story. (For details, check out his "Character Analysis.") Sure. It makes sense. He’s warm and sunny. Got it.
But Bella also describes Jacob as a rock – the rock that saves her from drowning after she jumps off the cliff. At first she believes she merely hit a rock in the current that’s sucking her to the bottom, but then she realizes it's Jacob:
The rock wasn’t cold like the water; it was hot on my skin. I realized it was Jacob’s hand, trying to beat the water from my lungs. (16.10)
Ever heard of "And I say also unto thee, That thou art Peter, and upon this rock I will build my Church; and the gates of hell shall not prevail against it" (Matthew 16:18, King James Version)? Jesus built the future and the life of his church on the apostle Peter. The Biblical connection makes even more sense since Bella mentioned earlier that Jacob was "a gift from the gods" (5.151).
You can also think about Jacob in terms of the Biblical figure. In Genesis 28, Jacob is the third patriarch, and has a dream in which a ladder or a staircases stretches from earth to heaven. During this vision, God tells him that he's given Jacob and his descendents the land of Canaan. (You can read more about the Biblical Jacob here.)
So maybe these connections to Peter and the Biblical Jacob are telling us about some of Jacob's essential qualities: he's dependable and a leader. So there might be more to him (in future sequels) that meets the eye. In many ways, Bella has already built her future on Jacob, because he saved her life. But what does his future have in store? And will he rise up to be a leader?