He is not a good speaker, not an eloquent man. Maybe Moses is humble and shy to go to the elders and the Pharaoh, but it is not (on the whole) honest. Moses had a good education at the court in Egypt and was powerful in speech and action (Acts 7:22); and his speeches in Deuteronomy are full of eloquence. Moses’ objection is also not relevant. God uses who he wants; he can use a staff to make clear his message, and he can use people who cannot perform well by themselves. He uses modest preachers, as is said in 2 Corinthians 4:7: But we have this treasure in jars of clay, to show that this surpassing power belongs to God and not to us.
God’s power is shown in weak people (2 Corinthians 12:9). Lastly, Moses’ objection is not respectful. He blames God that he gives him a mission without the right skills. But God gives the talents. Moses has to trust God who sends his Word through messengers. God’s Word shall not return to me empty, but it shall accomplish that which I purpose, and shall succeed in the thing for which I sent it
(Isaiah 55:11).
10 But Moses said to the LORD, “Oh, my Lord, I am not eloquent, either in the past or since you have spoken to your servant, but I am slow of speech and of tongue.”