In Islam, a female cannot marry unless she is able to understand marriage and is menstruating.

Aisha (may God bless her) was most likely to be 14 or 15

Back in those days 30 was the average age, hence half your life was fulfilled by the time you reached 15

This is why no Christians, Jewish, Idol worshippers, Pagans etc at the time ever raised such an allegation

Only today such an allegation is raised from ignorant and idiots