On average, when a girl is 13 years old, her IQ on an adult intelligence test will be in the normal range. The age of consent in Germany is 14. The age of consent in Uruguay is 12. The age of consent in Spain has traditionally been 13 and still is although it is in a limbo. The age of consent in Canada was 14 until a few years ago when the USA made them raise it. Phalometric studies, which measure male sexual arousal by penile blood volume, reveal that over 80% of males are just as sexually attracted to pubescent 12 year olds as they are to 18 year olds.
Evolutionary psychology theory strongly supports point 3, as males who reproduced with the full range of fertile females were far more likely to pass their genetics on, and to do so to a greater extent. The age of consent around the world was close to puberty up until the 1880's, when religious feminists groups invented the idea that it should be higher, originally done to lower prostitution rates Full sexual maturity, meaning tanner stage 5, is reached on average at age 14.5 in females, meaning that you cannot differentiate between a 14.5 year old girl and an 18 year old girl, based on sexual development.
About 25% of adult females will never pass tanner stage 4, which is reached on average around 13 years old. Underage teenagers also fall into the normal range of adult height and weight, although more so toward the petite side of normal, Tons of underage teenagers are having sex with each other and with adults and turning out perfectly fine, and your entire argument is based on made up bullshit that you have been brainwashed into believing and which has not a shred of legitimate evidence supporting it.
The brain of a human continues to develop until they are 25 years old, so you cannot use the lack of a mature brain to argue that a 15 year old cannot consent to sex but an 18 or even 24 year old can, and also see point 1 which shows that 13 year old brains support normal adult intelligences. Also, keep in mind that there are a lot of people who are very intent on lying about the facts, distorting reality, and doing whatever they have to do to manipulate your perception of the world.
There is an organized movement to demonize and criminalize empirically demonstrated as normal male sexual behavioral patterns. These people are filthy liars, and they have tried to infiltrate every group of significant power they are capable of infiltrating, in order to further their male hating agenda of bullshit. A prime example of this was their failed coup of the field of Psychology, in which their agents attempted to have sexual attraction to pubescent 12-14 year olds labeled as a mental illness called "hebephilia". Thankfully this attempt was REJECTED, and hebephilia is not a recognized mental disorder in the DSM, and the MAJORITY opinion of mental health professionals is that being sexually attracted to teenagers is NORMAL, and the opinion of the majority of people in dozens of first world countries from Germany to Italy to Uruguay is that it can be acceptable for an adult male to have sex with young teenagers!