I do math research. Isn’t it vain because angels and other aliens know math better than me anyway?
(I Corinthians 15:58) “Therefore, my beloved brothers, be … always abounding in the Lord’s work, because you know that your labor is not in vain in the Lord.”
This says that our work is not vain.
As I said in this sermon, our work helps to gain knowledge of how to overcome sin. During the pass of my research I receive not only research results but also unconsciously results of how to overcome sin which disturbs me to do good works, these results on how to overcome sin are novel for angels. That is, I discover something angels don’t know. So my work is not vain.