I like the mystic elements, including Hellenistic states of matter and Daoist motions of matter.
Even here, I count eight elements.
Darkness (empty space, negative void) (≈ Dao Soil, Space)
Light (energy, positive energy, consciousness)
Ether (forces, including gravity, electromagnetic, atomic, plus telekinesis)
Fire (plasma)
Air (gas) (≈ Dao Tree, Wind)
Water (liquid)
Earth (solid) (≈ Dao Metal, Crystal)
Tree (combining the four into a living, expanding, element)
Tree can be understood as its own element, a special combination of "the four" elements, or an aspect of Air, or an aspect of Earth.
For D&D purposes, I split the "electromagnetic" forces of ether, between "Fire" with Light and Radiant, and "Air" with Lightning and Thunder.
The Acid damage type is weird, but ultimately I decided it is part of the "Elemental Chaos" and represents an unstable primordial aspect of "Earth". There are a number of Evocation spells that are multi-elemental (Chromatic Orb, Prismatic Spray, etcetera), and I group all of these as "primordial" and corresponding to the Elemental Chaos, rather than any of the four elemental planes.
The Ethereal Plane is the "Fifth Elemental Plane".
The 5e Transmutation groups together themes of Earth, Plant, and Beast, plus shapeshifting and fabricating objects, which works well enough as aspects of "Earth".