The terms male/female, masculine/feminine, boy/girl and man/woman are all based on the same thing. To try and differentiate them as referring to different basic facts is what's causing the confusion.
Science defines sexual reproduction as the joining of a male gamete (sperm) and a female gamete (egg or ovum) to form a zygote -- which is a fertilized egg. That fertilized egg only remains a zygote for a brief period. When cells begin to divide, it becomes an embryo.
Biological science, pure and simple.
The terms male and female define the two sexes which contribute to the reproductive process. Based on that fact, males are further categorized as boys (pre-adolescent male humans) and men (adult male humans), while females are categorized as girls (pre-adolescent female humans) and women (adult female humans).
Contrary to the legal definition of an adult, in biology an adult is one who has gone through puberty and is capable of reproduction.
That's just science. Nothing too confusing.
As for gender, that can apply to electronic/electrical connections (male connector inserted into female connector), language (in Spanish, there are both masculine and feminine forms of most articles, nouns and pronouns. e.g. La Chica vs. El Chico. Having this construct embedded in the language reduces assumptions and confusion for the listener/reader as to who is being referred to.
The Left likes to say gender is "assigned" at birth. That's not true. Gender is assigned when the male sperm fertilizes the egg. Sperm can carry either an X or Y chromosome. The egg always has an X chromosome. So the XX pair is female, and the XY pair is male. What happens at birth is the person observing the gender based on genitalia and other physical signs records that observation. To say they "assigned' the gender is to make the decision sound arbitrary when it's based on observable facts. There may be a rare occurrence when an infant shows the genitalia of both genders. Usually in those instance only one set of reproductive organs is present, so the gender is based on additional observations.
The terms Men and Women are not philosophical. They simply differentiate the adult gender from the pre-adolescent gender. Nothing more. The terms are often used metaphorically (Be a man! You throw like a girl!). Someone saying "You swim like a fish" doesn't make you a fish. Usage does not determine the truth behind vocabulary. The fact is, the left is kidnapping the language and brainwashing us into believing any word can mean anything we desire.
When words can mean anything, they literally mean nothing.