Many theologians and atheists and people in general argue over which animals God is referencing in Job chapter 40 (the answer to which I’ll provide shortly #imho). By focusing on the animals we miss the greater point that God is making. God highlights the characteristics of a land and then a sea animal. His point to Job is if you cannot understand or grasp the concept of why these creatures were created, if you cannot meet their varying needs, if you cannot see their role in the universe then how can you begin to question God and His purpose? If Job cannot grasp what God is doing with and for these animals how could Job get and grasp what God is doing with and for humanity.
We know God has just demonstrated what faith in God can do; not just to Job but also to satan (and by extension to us). That same faith is what saved the Old Testament saints as they looked forward to the Cross and the New Testament saints and us as we look back to it. As to the animals God is referencing? They could easily be ones no longer in existence in our day. But the main point is they are identified as ones God created; ones He knows and created for His purpose. The same is true of you and me. God created us to know Him and more so than the animals to be recipients of His amazing love. Like Job, we just need to put our faith and trust in God even in the midst of the trials and tribulations of this world.