What is the catholic argument that justifies the usage of statues and pictures of Jesus Christ and saints?
Obviously this depends on the meaning of "usage". If you're using a statue to clobber an innocent person to death, clearly there is no Catholic argument that justifies this. This is called murder. Catholics think that's bad.
Treating a statue of Jesus as if the statue itself was Jesus or as if it had some sort of "divine element" inside is also bad. This is called idolatry, or the worship of something in place of God. There's no Catholic argument for this either, Catholics think that's bad.
Now think of a mother who shows a friend a photo of her youngest child. Think of a soldier who cherishes a picture of his wife that his youngest child drew. These people aren't worshipping other humans. Think of a barber who talks to the image of his client in the mirror while cutting hair. The barber isn't talking to the mirror. There is no Catholic argument here, and no need for one. Using images and statues in this way is ok, according to both the Bible and common sense.