I'm also a Catholic but you have to stay reasonable.
The idea of a purpose of mankind has been a debacle through all of religious history. The idea comes from two conceptual questions:
1) Who created the universe?
2) Why did he do it?
The idea of God created the universe using either a definition of God as a synonym for nature, or using nature as a method of God, answers the first question. A sort of divine, almighty power created literally out of nothing, something.
For the second question, we have to turn to philosophy. If we define God as a man-like creature, then we are easily convinced He must have had human motives as well. We can then compare God to a baker. To follow this logic, I'll construct a small scheme:
- A baker bakes bread.
Why does he bake bread?
- To have some money.
Why does he need money?
- To buy other goods.
... etc.
So the purpose of him making that bread is to obtain something in return. Now there are two possible perspectives to follow:
1) He wants love and our devotion in return to create a good, harmonious world.
2) He can't be defined as a human being using the Paradox of Epicuros:
The God of the Bible is all-loving, Omnipotent, and Omniscient. Why is there then Evil in the world and why doesn't he take it away?
* Either He knows it but can't take it away. Then He isn't omnipotent.
* Either He doesn't know it but He can take it way. Then He isn't omniscient.
* Either He knows it and He can take it away. Then He isn't all-loving since He doesn't take it away.
This would mean God can't be human, so he needs to be identified by something else. Some believers identify God with nature, since nature is a total of ecological, astronomical and biological processes able to create something out of nothing. Then the question of the purpose of men is irrelevant. It's equally irrelevant as the question 'What is the purpose of Warsaw?' or 'What is the purpose of Mt. Rysy?'
I hope this answer satisfies your curiosity?
MrComric