The second question: We were created on earth, so what is the most valuable thing therein? This question is related to the first one. If you know the purpose of your creation, you would know the most precious thing on earth. Thus, these two questions are one. If you know why you were created and the most valuable thing to do in this world, you would undoubtedly know the destination.

 If you contemplate in the kingdom of heavens and earth, you will know that there is a Great Creator for this universe. The universe tells you that there is a great purpose behind it, 

What is that purpose? The purpose is worship. It is to know Him, obey Him, and to be happy for being near to Him. Worship is the purpose for which the universe, man, and Jinn were created. 

Allah the Almighty says:

"And I did not create the jinn and mankind except to worship Me."

and says:

"O man! What has made you careless concerning your Lord, the Most Generous?

Who created you, proportioned you, and balanced you?"

 Human beings are created to be happy. If you know that you were created to be happy, you feel relieved, optimistic, honored, and that your existence is a blessing from Allah.