Greek - Petros - 4074 (Pétros) is an isolated rock (TDNT, 3, 100). "4074 (Pétros) always means a stone . . . such as a man may throw, . . .
versus
Greek - 4073 pétra, a projecting rock, cliff" (S. Zodhiates, Dict).
Matthew 16:18 And I tell you that you are Peter (Petros), and on this rock (petra) I will build my church, and the gates of Hades will not overcome it.
Jesus did NOT build His ekklesia on Petros (Peter).
Thou art Simon the son of Jona: thou shalt be called Cephas, which is by interpretation, A stone (Petros).
I believe Jesus was building his Church on faith which is the rock referred to.