Why begin with the Alphabet ?

Man must have developed the Alphabet (which is an abstract idea) long after he evolved
spoken Language (which is a set of concrete objects).

He must have discovered words and grammar (both abstract notions used to analyze
Complete Expressions) long after he discovered phrases and sentences.

Would it not be more Natural and healthy to teach complete expressions before we burden
children with abstract ideas like Words, Grammar, and the Alphabet ? More so since at that
age they are probably not ready to learn abstract ideas and analytical thinking ?

Is there any empirical evidence ?

Is it possible to test this hypothesis ?

I wasn't aware that we do start with the alphabet at all.
We have been teaching our kids how to talk and what things are called before simple letters. Even numbers come before single letters.

I agree with Curlyben... children are usually read to, or exposed to, stories and books from an early age, long before formal education. These books are often picture books with simple words and phrases that the children will hear repeatedly.
Children will pick up on these simple words using the pictures as clues... as well as in everyday conversation. They will start to learn environmental "reading" as they frequent familiar shops and other locations.
Phonemic awareness is just one component in learning to read and most often comes well after the child has already had much exposure to a wide assortment of words, phrases, and expressions.
The education of reading has gone through many cycles, often repeating itself with just new buzz words and catch phrases... an emphasis on phonics, then whole language, etc..
Currently it is probably at it's best simply because most educators realize one size does not fit all and children often do best when they have exposure to all of the components.
Certainly it will depend on where someone lives and goes to school. Different educational systems in different countries will often have varied approaches.