If current age of consent laws were in existence and followed throughout all human history, it's safe to say that very few of our family trees would make it back more than a few generations.
My paternal grandmother was married at 18, and my maternal grandmother at 16. Both of their husbands were 4 or 5 years older. And, they married older than their mothers did.
Honestly, most of these laws seem to be based on hysteria rather than thought.
I'm certainly not advocating for people marrying at 14 or 15, but I do think that we should recognize that there is nothing inherently wrong/immoral about doing so, and that the realities of modern life make that an unattractive enough option for most people that these laws aren't really all that necessary. It's not like many people really want to get married at 14 but don't because it's illegal.