I think we can all agree that, despite some attempts, it is nearly impossible to see any bulls, rams, crabs or whatever in the stars. So the constellations were not named for their shapes. To me it makes more sense that they would be names in honour of gods and myths. So I think this question is appropriate to this forum: How were the constellations named?
You may find this an interesting read: The Celestial River: Identifying the Ancient Egyptian Constellations
This astronomical study of the night sky in ancient Egypt, using modern software, demonstrates that the emblems of the districts of Upper and Lower Egypt represented ancient constellations that were rising, setting, or culminating in sequence. The “emblem constellations” indicate that the ancient Egyptians possessed early representations of many of the classical constellations known to the Greeks, such as Leo, Scorpius, Aquila, Aquarius, Taurus, Orion, Canis Major, and Lepus.
The analysis of the emblems of Upper and Lower Egypt enabled a hypothetical identification of 36 ancient Egyptian constellations. Furthermore, 28 out of the 38 Egyptian constellations are nearly identical matches, both astronomically and iconographically, when compared to the Ptolemaic list of 48 classical Greek constellations.