Well for starters, Bani-Israel had similarly those who possess the authority from them, mainly, Messengers but mixed their course and authority with following leaders not appointed by God. A great portion of Quran is devoted to how the false authority of religious clergy was mixed with that of divine authority of leaders appointed by God, mainly the Messengers.
And it because they broke the covenant with respect to their Messengers who after Moses, were Twelve Navigating Captains, they twisted God's words and their hearts became hard while doing so.
So they were cursed as a result because they didn't take the covenant seriously, but they were meant to hold on to no less and no more than Twelve Navigators that would succeed Moses.
And the number taken is important then, as it's important to have a number for the Ulil-Amr, lest people choose whatever leaders they want to follow for religion.
Lest falsehood becomes indistinguishable from truth.
The Ulil-Amr in clear context is chosen pure leaders appointed by God.
And so 5:12 is emphasizing on a number and wisdom of manifesting a number.
And it because they broke the covenant with respect to their Messengers who after Moses, were Twelve Navigating Captains, they twisted God's words and their hearts became hard while doing so.
So they were cursed as a result because they didn't take the covenant seriously, but they were meant to hold on to no less and no more than Twelve Navigators that would succeed Moses.
And the number taken is important then, as it's important to have a number for the Ulil-Amr, lest people choose whatever leaders they want to follow for religion.
Lest falsehood becomes indistinguishable from truth.
The Ulil-Amr in clear context is chosen pure leaders appointed by God.
And so 5:12 is emphasizing on a number and wisdom of manifesting a number.