Interesting take. I think very plausible on the Tom front. I like the well analogy, that works pretty “well.”
On the god front, close as well, but I can’t say much since a lot of that is the topic of II and III.
However, one key thing in magic that is only barely alluded to on the site here, is the idea of a Mana Pool. A mana pool is basically a battery into which mana users pour mana to draw on at a later date. Typically they are made out of crystals, and are used hold mana for magic items. Thus magic items that cast spells get their mana from these pools, which have to be recharged periodically.
To recharge the magic item you have to take the item to a wizard (or priest or someone of the profession that made the item) and get it recharged.
Many of the amulets and rings that wizards (for example) wear are not “magic per se” but rather mana pools to give them additional mana reserves in combat. The wizard who makes the mana pool has a link to it and they can charge it or draw on it as needed.
There is also, I will say, an analog of this for deities and their avatars called a God Pool. It’s a giant well from which deities and their servants can draw power, and to which avatars funnel mana from priests from worshipers into.