To scripturally prove within this context that 14 generations does not equal 560 literal years is easy:
From Abraham to David are fourteen generations - Mat 1:17
Abraham died at 175yrs old - Gen 25:7
Abraham had Isaac at 100yrs old - Gen 21:5
Isaac had Jacob at 60yrs old - Gen 25:26
Jacob entered Egypt at 130yrs old - Gen 47:9
Therefore, Jacob entered Egypt 115yrs after Abraham died
Therefore, Jacob entered Egypt 290yrs after Abraham was born
Jacob/Israel was in Egypt 430yrs - Exd 12:40
Therefore, Israel left Egypt 545yrs after Abraham died
Therefore, Israel left Egypt 720yrs after Abraham was born
David began to reign at 30yrs old - 2Sa 5:4
David reigned 40yrs - 2Sa 5:4
Solomon's 4th year of reign was the 480th since Israel left Egypt - 1Ki 6:1
Therefore, David was born 406yrs after Israel left Egypt
Therefore, David died 476yrs after Israel left Egypt
Therefore, there are 951yrs from Abraham's death until David's birth (14gen Min)
Therefore, there are 1196yrs from Abraham's birth until David's death (14gen Max)
Therefore, the 14 generations from Abraham to David would each average 67.93yrs minimum and 85.43yrs maximum.
The clock for the 430 years started ticking when Joseph entered Egypt, not when Jacob entered Egypt.
40 Now the sojourn of the children of Israel who lived in Egypt was four hundred and thirty years. 41 And it came to pass at the end of the four hundred and thirty years--on that very same day--it came to pass that all the armies of the Lord went out from the land of Egypt.
By your "math" Cyrus would have given the decree 1000 years before Messiah the Prince.
You have proved nothing!
JLB