yep. From reading Bret Devereaux's Acoup.blog, I've learned that especially with arrows, height is an advantage - if you're firing down on someone from a position above them, you can aim easier, and your arrow is accelerated by gravity. Conversely, if you're firing up at someone from a position below them, gravity is working against you, and it's harder to aim.

This is why they build seige towers back in the day - to give the attackers a position higher than the beseiged city's walls from which to fire down on the defenders.