You are wrong here. All men are born sinners. No one has to be taught to be sinful. Every babe born, as mild and meek to us as they seem, are babes born in sin and natural to sin. They are selfish by nature.
Look above at the scriptures you quote SJ. Nowhere does Jesus declare that children are innocent. You are applying that understanding based not on the text, but on your life observations and desires.
One needs to be true to the text. We need to be as children... that is - we need to be dependent upon God. That we desire to learn, to be near, to be provided for, and be taught by God. This has nothing to do with a child being innocent. That would be self-righteousness.
I understand your desire to build a case that man has lost his innocence thus to be like a child, but that is not the way of salvation. The text is about child like dependance. Your post declares all men are born innocent [IE not guilty, sinless], as I've re-quoted above.
And again, you still miss my heart of instruction, but that's OK.