The First Animal Created.

Hippopotamuses are probably the first animals created by God 

Let’s check out Job 40 to see it. Job 40:15–19

15 “Look at Behemoth, which I made along with you and which feeds on grass like an ox.

16 What strength it has in its loins, what power in the muscles of its belly!

17 Its tail sways like a cedar; the sinews of its thighs are close-knit.

18 Its bones are tubes of bronze, its limbs like rods of iron.

19 It ranks first among the works of God, yet its Maker can approach it with his sword.

Behemoth is translated by hippopotamus in many other versions. And “it ranks first among the works of God“ is a way of saying “it was the first animal created”.