i understand and that's a good analysis of the gameplay differences. but im trying to think of it lore wise, not gameplay.
in universe, it's not like people have a character creation screen and they decide what class they're gonna be.
maybe someone is really devoted to their god and therefore you would call it a cleric, someone decided to make things right in the world and get some training in fighting skills and you would call that a paladin. but the lines are blurred.
in the situation described in the op though, it seems like the game is pretty much describing a druid, except that it's not.

it's like saying: my character is a paladin. he's proficient in daggers and short swords, sleight of hand, has high dexterity and low strength, he's also really good at sneaking around and is able to decieve people efficiently.
sir, that's a rogue.
If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.

let's say someone meets the character described in op.
he's an outlander, so he lives in the wild away from civilization.
he worships silvanus, god of nature. he's REALLY into him, so he would follow his beliefs and live a lifestyle to reflect that.
he casts divine spells of a druid, granted by his god (silvanus)
how is that not a druid? silvanus wouldn't even have a church in cities, he would have groves and temples curated by druids. in fact, a cleric of silvanus is literally a druid.