Many, indeed! You are incorrect to make polygamy to be a extremely rare exception under biblical code. One modern example: The Jews of Yemen practiced polygamy until they were returned to Israel in the 1950s and 60s. Second example: Samuel’s parents.
I said there were "many"--I qualified that by saying that there weren't "many" as far as the major "patriarchs" went.
Adam was not. Noah was not. In my opinion, sleeping with "the help" one night for surrogacy purposes doesn't make one a "polygamist" (Abraham). Isaac was not. Moses had two wives, but we don't know when the first one died. Aaron was not. Joshua was not. The prophets such as Ezekiel, Isaiah, Jeremiah, Daniel and the later prophets were not.
Second example: Samuel’s parents.
Exceptions don't prove the rule. In fact, if you make a list of Old Testament characters who either were polygamists or had concubines, you basically conclude that they slept with somebody other than their wife...
...(a) in their pre-covenant-with-God-stage (the pre-covenant Abram did it--not Abraham...and the pre-covenant Jacob did this, not the re-named Israel);
...or (b) they were shady characters otherwise.
Of course, there's exceptions to (a) and (b) above...that would include David, Gideon and Caleb.
One modern example: The Jews of Yemen practiced polygamy until they were returned to Israel in the 1950s and 60s.
So what? I could pull out all kinds of Old Testament Jewish examples of Jews clinging to particular idols. Sometimes it was a golden calf. Other times, it was temple prostitution. Sometimes it was embracing the gods of the peoples around them (Baal, Ashtoreth, etc.). And just because idolatry went on generationally for some Jews as some point in their history doesn't mean it was "the standard."
The fact is that revengeful, violent Lamech was the Biblical instigator of polygamy (see Gen. 4). For some reason, people want to start with Abraham as the prototype. He wasn't even a practioner of polygamy. Lamech was the guy. As for the practice of both polygamy and surrogacy in ancient times, that custom cradled among the ancient Mesopotamian pagans.
The Jewish tribes were always struggling with pagan practices, as are Christians today!