The Mikaelsons as characters are perfect, honestly the best in the series but I feel they don’t work as being the first Vampires. The reason for this does sound stupid but it’s because they aren’t old enough, as the writers kinda gave the proper old one age and title to Silas and Amara who are technically the first vampires. Even when the Mikaelsons meet Silas he beats them pretty easily and he’s not even at full strength, which kinda takes away from the idea that the Mikaelsons are the first and most powerful vampires even though that’s not the case.