Firstborn and zombie cattle

Exodus 12:29 says, “And it came to pass, that at midnight the LORD smote all the firstborn in the land of Egypt, from the firstborn of Pharaoh that sat on his throne unto the firstborn of the captive that was in the dungeon; and all the firstborn of cattle.

12:30 And Pharaoh rose up in the night, he, and all his servants, and all the Egyptians; and there was a great cry in Egypt; for there was not a house where there was not one dead.”  Usually the Pharaoh was actually the firstborn of his father so why is the sitting Pharaoh still alive.  Also many of the adults are probably firstborn.  Did they die too?  And once again, the cattle, I thought they were all dead earlier.  How do they keep coming alive?  Are they zombie cattle?