I'm not arguing that. According to your profile you are 17, so you can't do any of those things; drink, smoke, etc. either, but that doesn't mean that its legal for someone to murder you.
If a state wishes to pass a law making it lawful for seventeen year-olds to be murdered, I know of no provision of the Constitution which will prevent it from doing so.
The equal protection clause could mean any number of things. It might mean that states have to treat fetuses and adults equally, by protecting the lives of both. It might also mean that states have to treat rich and poor equally, by taxing both at the same rates. It might also mean that states have to treat homosexuals and heterosexuals equally, by legalizing same-sex marriage.
Almost all laws discriminate between individuals in one way or another. Abortion laws differentiate between fetuses and adults; tax laws differentiate between rich and poor; marriage laws differentiate between homosexuals and heterosexuals. Under your theory, all of these laws would be unconstitutional, because they give one class of citizens (adults, poor people, or heterosexuals) more "protection" than another class. Needless to say, a literal reading of the equal protection clause cannot possibly be sustained.
In the words of Sir William Blackstone, "the most universal and effectual way of discovering the true meaning of a law, when the words are dubious, is by considering the reason and spirit of it; or the cause which moved the legislator to enact it." The most cursory glance at history would indicate that the purpose of the equal protection clause was to obliterate distinctions between the races. It follows, therefore, that the clause prevents any state from engaging in racial discrimination. But there is no evidence that other forms of discrimination (such as age discrimination) are forbidden.