There are no discernible goals in his actions.

Absolutely. And the complete lack of a goal leads to a noticeable decrease in the quality of the game. And I'll say this specifically for those who like to "play for fun" – a game with good strategic ideas and original tactical concepts brings much more enjoyment than simply "running around with a unit."

If it's not possible to increase power through magic or brute force (including creating a powerful stack by hiring many heroes).

Well, now we've come to the question of choosing the so-called "main" hero. Let's try to figure out what kind of hero that might be.
The general line of reasoning: So, I have a map that's not too small, but not too big either. It seems to be a Medium size. On this map, considering the amount of resources and gold I have, I'll build mages in the first week. And on the first day of the second week, I'll start expanding. An approximate army for the first day of the second week (121): 6 mages, 8 birds (if I don't lose them), maybe 20-30 halflings will remain after the first week, 5 pigs to cover the archers and provide support, I probably won't be able to buy golems – I probably won't have enough gold. I'll look for a foundry – they make steel golems from iron golems for free. But for now, let's assume there are no golems.
Okay, in this army, there are two archers (it would be good if the main hero could learn the Archery skill). It's difficult to estimate the total damage, but it seems that the hero-mage will deal around 150 damage (this is just speculation, without calculations). So, a hero-barbarian will deal around 195, a knight 180, a sorceress, wizard, or necromancer – 150, a necromancer – 165. But! To build mages, you need a magic guild, and there, there might be a magic archer. And this gives mage heroes 20 (and a necromancer 30) damage. So, in principle, you can choose a mage. What's annoying is that you'll need to storm at least 3 Castles. So, you need a decent defense and ballistics.
The final verdict.
If you have a good opportunity, a knight hero is quite interesting on this map: he has ballistics and good defense with potential for growth.
Also, a native wizard hero is a perfectly normal option (he has defense + a basic Stoneskin spell), but he will need ballistics. Another quite decent option: a necromancer hero. High magic power combined with useful scouting for an early-game hero, and a very useful starting army for the first week.
We won't go into a necromancer strategy or seriously consider other heroes.
Now let's look at the Castle and see who they offer us. They offer us a native wizard hero and a witch hero. Well, then we'll play with the starting hero for now. Right?
No! Not quite!
We leave 1 pig with the starting hero and send him off to scout and explore. And with the second (or even third, fourth) hero, we take his army and the units bought in the Castle. This way, the army of several heroes gathers together and becomes a formidable force.

But it seems you also found flaws in his building order?

So, we decided that the MAGE hero will be our main hero (this is confirmed by further development, in particular, by taking chests for experience). And, having decided this, we build... a statue. Of course, when playing a magic-focused game, you need to build a magic guild so that the hero can learn the magic available there. Yes, this magic may not be very useful, but the probability of good spells appearing is high enough. And also: troops can be brought to the hero by other heroes (passed along a chain of heroes), but magic from a magic guild cannot be passed along a chain of heroes.

Colleagues, let's continue the discussion!