Here is a hint about them and where they come from:
Rev. 5:8 And when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps,
and golden vials full of odors, which are the prayers of saints.
9 And they sung a new song, saying, Thou art worthy to take the book, and to open the seals thereof: for thou wast slain,
and hast redeemed us to God by thy blood out of every kindred, and tongue, and people, and nation;
10 And hast made us unto our God kings and priests: and we shall reign on the earth.
so we can see that they represent the saints of God.
We may have to look at the beast as characters of the saints.
of a man - from mankind
of a lion - strong - Eph. 6:10
of a calf - sacrifice of yourself - Romans 12:1
of a eagle - good visions, rises above the flesh and sets high in heavenly places. Eph. 2