The deepest problem with the Cleric class is its cosmological setting assumptions. Other settings need to use this core class as well.
Religion is a session zero topic, to ensure all reallife players are comfortable.
The Cleric class must allow the player to decide the sacred tradition for ones own character concept. The class requires narrative flexibility with a fluid, inclusive, and customizable approach to sacred traditions. Any kind of sacred tradition: polytheism, monism, animism, whatever.
In D&D, Divine power is the magic of the Astral Plane, including its thought stuff, alignments, concepts, symbols, paradigms, and mindcapes.
The Cleric class is a Gish - a full caster that is competent in melee combat. The spell schools that this class is known for are: Abjuration including Healing, Divination, Planeshifting, and Necromancy including Undead and Fiends. This is a distinctive thematic for a kind of Mage, an Astral gishy one.