The call of Moses was revelation of universal truth
Here is something from the revised ISBE (International Standard Bible Encyclopedia, 1988) about why the call of Moses was revelation: "God's revelation is His personal self-revelation. He Himself came to Abram, spoke to him (Gen. 12:1-3), and made him His friend (Jas. 2:23). He 'used to speak to Moses face to face, as a man speaks to his friend' (Ex. 33:11). He knew Moses by name and gave him His own covenant name (Ex. 33:17; 3:13-15). Here was no impersonal disclosing of new facts or teachings, but the self-revealing of God in person." (Vol. 3, pp. 162-163)
Here is something from the revised ISBE (International Standard Bible Encyclopedia, 1988) about why the call of Moses was revelation: "God's revelation is His personal self-revelation. He Himself came to Abram, spoke to him (Gen. 12:1-3), and made him His friend (Jas. 2:23). He 'used to speak to Moses face to face, as a man speaks to his friend' (Ex. 33:11). He knew Moses by name and gave him His own covenant name (Ex. 33:17; 3:13-15). Here was no impersonal disclosing of new facts or teachings, but the self-revealing of God in person." (Vol. 3, pp. 162-163)