He said he hailed from a small village, but said village is discovered to be century old ruins.
So I thought of two main options for this:
1. Solas' has indeed came from said village and he is under the same circumstances as Flemeth - either he found Fen'Harel in the fade or he was found himself in a desperate situation and called Fen'Harel. Now this seems a very unlikely answer. First thing first, for him to have found Fen'Harel in the fade would've meant Fen'Harel locked himself in with the other gods or something of that sort, so let's say Fen'Harel came to him. Now that we've settled that, we need to rethink the way we approach how he acts and who he is. Unlike Flemeth - Solas acts as if HE is Fen'Harel. Speaks of mistakes done by a young elf, seems to take it really personally when Morrigan tries to understand why Fen'Harel's statue is at the Temple... It doesn't seem like Solas is a host (unless he is a very passive host who is really connected Fen'Harel's spirit). So if we continue with this theory it means Fen'Harel took over the body of an elf. This seems wrong, Flemeth said that "A soul is not forced upon the unwilling", which means that the elf Solas was before just accepted losing his body? If so it must mean Fen'Harel must jump bodies, since, even though the village is centuries old, the elves of the time were not longer immortal, centuries =/= thousands of years. So if that's true it'll also must mean Solas didn't know the village was ruined, and that's why he said he hailed from there.
2. Solas was always Fen'Harel, there was never a 'mortal' Solas. He saw the village in his travels to the fade, or in one of his physical travels a long time ago and decided to use it as his background story. He didn't know, however, that the village was ruined.
3. Solas was always Fen'Harel + several accumulating centuries = thousands of years, in an assumption Leilana just guesstimated badly.
4. Solas was always Fen'Harel + the village was itself really old and was ruined some centuries after Solas' departure. He just wasn't aware of it.
I lean towards 2 & 4.