"When Little Gregory was reading through the Psalter, and he came to the last one, and he ran to Mommy and said, "I know about David and Goliath! Can we sing this one now? Teach me it!" is that when Mommy, a little embarrased turned to him and said, "Oh son, that one isn't in the Hebrew Psalter! We don't sing it. Just ignore it." ?!?" No, she would instruct her son responsibly that such a song could be sung at home, but has no place in the Hebrew Canon for the inspired hymnal of the church. Wouldn't that be the responsible thing for someone to do? I think 1) you have to determine whether it was in the the Hebrew Psalter, and 2) whether the Jews would have accepted it in the psalter. After that, you can make a solid conclusion as to whether the Jews would have used it in worship, and i think its very obvious. That does not under estimate, though, the value of your question.