Did God make the ancient israelites also worship a goddess?
The answer is no. So why did Moses use the serpent on the pole? It was a foreshadowing of things to come. John 3:14-15 "And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up, that whoever believes in him should not perish but have eternal life". The Lord set up situations ,in the old testament, to shed light on things that would come to pass when His Son came to Earth as Savior. There are others as well. Matt 2:15 "and was there until the death of Herod, that it might be fulfilled which was spoken by the Lord through the prophet, saying, "Out of Egypt I called My Son." (found in Hosea 11:1 refering to Israel) The story of Abraham (father) willing to sacrifice Isaac (his son) is a picture of Christ also. Hopes this helps.
God Bless!