I do not think there should be an age of consent, primarily because I do not think that the length of time since a person emerged from the womb is a useful indicator of anything. Having an age of consent is too often seen as to be saying 'people under this age should not have sex'. Which makes sex a forbidden area for those under the age. Which denies them the right to learn about this important area of life as they learn other things. An age of 'consent' implies that those younger than this age cannot consent to sex with each other, and thus I disagree with the concept.
Sexual maturity is both physical and mental.
A legal age of consent is presumably there as a protection, because adults have greater power in this world, and can force children to do thing they don't necessarily want to, or persuade them that they do when they don't, so children need protection. For instance, men have for quite a while tended to have power over women, and bosses have power over their employees. Thus we need laws to protect against abuses of power hierarchies, and we do - sexual harassment laws. In both the cases I mentioned at the start, the abuser was caught, found guilty of a crime, and sentenced. And even though the age of consent was brought into the proceedings, I maintain that the laws against non-consensual acts and harassment would have sufficed.