"Yes, even 'Jehovah' himself was referred to as a bull and depicted with bovine imagery". I never ever heard of this! Can you tell me where you find this information?
Well, there is much evidence of this both in the OT and in archaeological discoveries:
1) 1 Kings 12:25-33 relates how King Jeroboam I set up two golden bulls in Bethel and Dan, which he presented with the declaration, "Behold, your god (hnh 'lhyk) who brought you out of Egypt." There was no other god than Yahweh credited with the act of bringing Israel out of Egypt and no other god is named in this passage.
2) In Exodus 32, Jeroboam's act is retrojected back to the exodus itself and attributed to Aaron; this reflects the Aaronid priesthood that served Jeroboam's bull cult in Bethel. Jeroboam's declaration is slightly reworded in v. 4: "These are your gods ('lh 'lhyk) who brought (h`lwk, plural) you out of Egypt." The plural is due to the ambiguous phrasing in 1 Kings 12:28 wherein the plural would pertain to the two idols that Jeroboam made of the same god to be erected in two locations (Aaron's declaration is corrected to an unambiguous singular in Nehemiah 9:18). Again, there is no indication that this is a god other than Yahweh; in fact, in the very next verse Aaron builds an altar in front of the golden calf and he declares: "Tomorrow there will be a feast to Yahweh" (v. 5). Clearly, the bovine idol was intended to be a representation of Yahweh, at whose altar the sacrifices for the feast would be made. Unbeknownst to Aaron in the narrative, Yahweh had already decreed that no images were to be made to resemble creatures on the earth (Exodus 20:4).
3) Bethel, the center of the Aaronid priesthood and the location of one of the golden calves, was an old patriarchal cultic site revered by the patriarchs in Genesis, which was specifically associated with the god El (i.e. Bethel means "house of El", cf. El-Elyon and El-Shaddai in the patriarchal traditions) and El was identified with Yahweh in OT texts. El was referred to as "Bull El" in Canaanite texts (e.g. KTU 1.6 iv 10-11) and this bovine imagery appears in the archaic patriarchal poem in Genesis 49:24 which, in a constellation of titles and descriptors associated with El (including Shaddai, Olam, and "breasts and womb") refers to the "Bull of Jacob". In the much later Psalm 132:2, 5, this title "Bull of Jacob" is applied to Yahweh.
4) Yahweh is also described with bovine imagery in Numbers 24:8 as having horns "like the horns of a wild ox."
5) The Bethel bull-cult is mentioned in Hosea 13:2 which mentions that the people of Ephraim (where Bethel was located, cf. the condemnation of Bethel in Hosea 10:15) "kiss the calf-idols". In this passage Baal is mentioned since Yahweh was identified with Baal in the northern kingdom (cf. Hosea 2:16 wherein Yahweh is called by the Israelites "my Baal", and cf. the many Baal terms and imagery which are applied to Yahweh in the OT, e.g. Deuteronomy 33:2, Judges 4-5, 1 Samuel 12:18, Psalm 18:7-15, Psalm 29, 68:4-9, 74:13-14, Isaiah 14:13-14, 27:1, 30:19, 51:9, Jeremiah 3:3, 5:24, 10:13, 14:4, Amos 4:7, Habakkuk 3:3-11, Haggai 1:7-11, Malachi 3:10, etc.). The royal enthronment psalm in Psalm 2:11-12 also uses the motif of kissing in reference to Yahweh worship.
6) Bulls and calves are common in tenth and ninth century BC cult objects from the northern kingdom, such as the Tanaach cult stand. One Samaria ostracon has an inscription that reads "Young bull is Yaw".
7) The Kuntillet Arjud pithos from the early 8th century BC has a benediction attributed to King Joash of Israel that gives a blessing by "Yahweh of Samaria and his asherah", and next to the inscription is a large figure with bull's head, hooved feet and tail and a similar smaller female figure with breasts. The "Yahweh of Samaria", recalling the "young bull of Samaria" of Hosea 8:6, is probably depicted by the male bovine figure and his "asherah" (i.e. his consort) is depicted by the smaller figure.
8) Most telling is the Amherst Papyrus from the third century BC which contains the traditions of Israelites from Samaria who settled in Egypt after the dispersion of the northern tribes. This text, which has many traditions relating to the Assyrian conquest and the northern kingdom, contains a lot of information about the Bethel bovine cult. It refers to "Yaho our bull" as the "lord of Bethel" (XI.17), and the practice of kissing the calves of Bethel: "Let them kiss your bulls, let them desire your calves, Exalted One, the calves of your ??? [lacuna]" (V.12-22). The passage of XI.11-19 is thought to be a descendent of the actual prayer used in the Bethel bull cult and it is closely paralleled by Psalm 20. What makes this probable is that this prayer is also echoed in 2 Chronicles 13:8-12 in Abijah's condemnation of Jeroboam and his calf-cult.
