Okay, you're right about those being circumcised in Egypt. But:
Your carcasses shall fall in this wilderness, and all of you who were numbered in the census, from twenty years old and upward, who have grumbled against Me. Not one shall come into the land where I swore that I would make you dwell, except Caleb the son of Jephunneh and Joshua the son of Nun. But your little ones, whom you said would become a prey, I will bring in, and they shall know the land that you have rejected. -- Numbers 14
So, those who were too young to be counted as fighting men at the time they entered the wilderness survived to enter Canaan, and they would have been circumcised.
There were none younger they were cast out (exposed) to die...
Acts 7:17 ¶ But when the time of the promise drew nigh, which God had sworn to Abraham, the people grew and multiplied in Egypt,
18 Till another king arose, which knew not Joseph.
19
The same dealt subtilly with our kindred, and evil entreated our fathers, so that they cast out their young children, to the end they might not live.
20
In which time Moses was born, and was exceeding fair, and nourished up in his father’s house three months: {exceeding fair: or, fair to God }
21
And when he was cast out, Pharaoh’s daughter took him up, and nourished him for her own son.
This was being done at the time Moses was born....Aaron was not cast out....But by the time of moses birth this was happening
5 ¶ And the daughter of Pharaoh came down to wash herself at the river; and her maidens walked along by the river’s side; and when she saw the ark among the flags, she sent her maid to fetch it.
6 And when she had opened it, she saw the child: and, behold, the babe wept. And she had compassion on him, and said, This is one of the Hebrews’ children.
7 Then said his sister to Pharaoh’s daughter, Shall I go and call to thee a nurse of the Hebrew women, that she may nurse the child for thee?
By the way....
5 Now all the people that came out were circumcised: but all the people that were
born in the wilderness by the way as they came forth out of Egypt, them they had not circumcised.
By the way....
7 And their children, whom
he raised up in their stead, them Joshua circumcised: for they were uncircumcised, because
they had not circumcised them by the way.
Moses was hid three months.
Pharaoh's daughter SAW He was a Hebrews child.
5 ¶ And the daughter of Pharaoh came down to wash herself at the river; and her maidens walked along by the river’s side; and when she saw the ark among the flags, she sent her maid to fetch it.
6 And when she had opened it,
she saw the child: and, behold, the babe wept. And she had compassion on him, and said, This is one of the Hebrews’ children.
7 Then said his sister to Pharaoh’s daughter, Shall I go and call to thee a nurse of the Hebrew women, that she may nurse the child for thee?
