The adamic alphabet seems to cover the entire Greek alphabet including even more letters and symbols, like sampi, heta (which I thought was just the origin of eta, but apparently not), yot, koppa etc... From the source:
Adamic alphabet is world's first vowel+consonant phoneme-level script, invented as such by the Greeks, which features both vowels and consonants on equal level, which as such is most suitable for writing world's first human language, known as Adamic tongue. Adamic alphabet is also used for Adamic digit system.
I have found another source here that seems to have studies the background of the Greek alphabet in detail. There is no mention of the adamic alphabet, and their description of the origin is different:
The Greeks were the first Europeans to learn to write with an alphabet, and from them alphabetic writing spread to the rest of Europe, eventually leading down to all modern European alphabets. Incidentally, the Greeks tried writing once before. Between 1500 and 1200 BCE, the Mycenaeans, an early tribe of Greeks, adapted the Minoan syllabary as Linear B to write an early form of Greek. However, the syllabary was not well suited to write Greek, and the exact pronunciation of Mycenaean words remains somewhat obcure. The alphabet, on the other hand, allowed a more precise record of the sounds in the language.
From the shape of the letters, it is clear that the Greeks adopted the alphabet the Phoenician script, mostly like during the late 9th century BCE. In fact, Greek historian Herotodus, who lived during the 5th century BCE, called the Greek letters "phoinikeia grammata" (φοινικήια γράμματα), which means Phoenician letters.
Is the adamic alphabet simply an even earlier precessor to the Greek alphabet?