I have shown how history has disagreed with you. If God did not approve of something, God would be clear God does not approve of it and would be clear when it is time to stop. Please provide explicit verses showing God not approving and explicit verses saying to stop.
As I said many times, creation itself shows us His plan. Genesis 2 says a man (singular) will cleave to his wife (singular) and the two (not five) become one flesh. Just because men practiced polygamy and God did not smite them does not mean He approved of it. Kings also mentions how God commanded that kings over Israel must not take multiple wives.

