Overlap is an issue. Which is precisely why they were originally going for the harpy, a myth unit. A choice that was heavily rejected. And while I had and have no particular issue with the idea of a myth unit as a unique fortress unit, I wasn’t over the moon about the Harpy either.
The Devs learned now, from feedback, that overlap in the greek fortress unit department is preferrable to non-human units amongst their audience.
The solution, as has been pointed out by several users too, would have been hybridisation between troop types. Something that’s not purely archer, infantry or cavalry, but a combination. Like a cavalry-archer, as often suggested. Which is already a thing with the Turma, the charriot-archer, and I think a japanese cavalry unit (not sure about that one. There’s also a cut chinese unit, that’s still available in the editor)
Tiger-Cavalry combines Cavalry and infantry by only having the horse die the first time, and letting the rider continue fighting on foot as an infantry guy.
That is why I suggested the functionality of the Immortal from Tale of the Dragon to be brought back.
Making it a unit that combines infantry and archers, by switching between bow and sword depending on how far away the enemy is. (or, alternatively, the push of a button)
There are, to my knowledge, no non-hero, non-myth-unit units that can swap between a ranged and a meelee mode in AoM, Retold right now.
Would a siege unit have been more fitting? Possibly. But it also would have been more boring.