I would not say that Moses' faith allowed the miracles, i.e. was required. God's will concerning Israel could not be thwarted.
And the LORD said unto him, Who hath made man's mouth? or who maketh the dumb, or deaf, or the seeing, or the blind? have not I the LORD? Now therefore go, and I will be with thy mouth, and teach thee what thou shalt say.
And he said, O my Lord, send, I pray thee, by the hand [of him whom] thou wilt send.
And the anger of the LORD was kindled against Moses, and he said, [Is] not Aaron the Levite thy brother? I know that he can speak well. And also, behold, he cometh forth to meet thee: and when he seeth thee, he will be glad in his heart. And thou shalt speak unto him, and put words in his mouth: and I will be with thy mouth, and with his mouth, and will teach you what ye shall do.
And he shall be thy spokesman unto the people: and he shall be, [even] he shall be to thee instead of a mouth, and thou shalt be to him instead of God.
And thou shalt take this rod in thine hand, wherewith thou shalt do signs. - Exodus 4:10-17
God's will concerning Israel was not thwarted by their lack of faith.
I do like the typo of earthy (archaic for worldly). Can you expound on the above? What do you mean stuck with a priesthood? Also, Aaron started the miracles in Egypt, stumbled (maybe? Some scholars argue that the calf was a symbol of Yahweh) at Sinai, but then is washed and anointed at the tabernacle and granted a priesthood. What are you getting at?