But the main question is: will this tactic work in a game against a human player?

I don't think so. The catapult isn't particularly effective against a human player because killing them in their castle is always problematic and only possible with a significant advantage; otherwise, you need to try to catch them in the field. However, the ballista is a good skill for siege weapons, and some people also like the tent (although I haven't used it much). But if the game is relatively long, I would prefer education. And logistics are also essential for your development. If the opponent isn't playing a faction that potentially allows for the appearance of Dark creatures, it's better to take defense instead of anti-magic (or maybe it's better in any case, I don't know).
Also, I'm not at all sure that you'll encounter a Mentor in a game against a human player.