Many have died in the womb and never had the opportunity to sin

DRK:

can you prove that biblically ?

Yes.

Rom_3:23 For all have sinned, and come short of the glory of God;
Rom_5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned

You skipped one verse:
Romans 5:14
Nevertheless death reigned from Adam to Moses, even over them that had not sinned after the similitude of Adam's transgression, who is the figure of him that was to come.

Note that some died who had not sinned. And that remains the case as many have died in the womb and soon after, never having had the opportunity to sin. Therefore the Scripture is proven true.

Romans 3:23 and 5:12 are references to unbelievers. Scripture says:
Psalm 14:1
The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good.

Mary was a sinner like every other human on earth.

Provide the verse that says that Mary sinned.

If you listening to a man to teach you bible that could be dangerous....

That depends on which man. We submit to, obey and follow the faith of our Rulers in the Church. Scripture tells us to do so: 

Hebrews 13:7
King James Version (KJV)
⁷ Remember them which have the rule over you, who have spoken unto you the word of God: whose faith follow, considering the end of their conversation.

It is, however, dangerous to listen to Protestant teaching on Scripture.

Psa 118:8 It is better to trust in the LORD than to put confidence in man.

We trust in the Lord, that is why we trust His servants:

Hebrews 13:17
King James Version (KJV)
¹⁷ Obey them that have the rule over you, and submit yourselves: for they watch for your souls, as they that must give account, that they may do it with joy, and not with grief: for that is unprofitable for you.

Why don't you?

Sincerely,
De Maria