What is the strength of humankind?

In general, I'm interested in the question of what makes humans strong? Their faction ability is quite weak, giving an additional 20% damage on counterattacks. To use it to its full potential, meaning to upgrade warriors to the next level, you need a huge amount of gold, which is not always available. I remember on a map where there were many gold mines, I gathered knights in a number two and a half times greater than the enemy's 6th-level creatures from other factions, and I was invincible. So, when there is gold, the knight is not that bad, but I would like to consider an example when there is no gold, and the only bonus from the faction ability is a slightly enhanced counterattack. To avoid playing on any map for too long, I simply chose a duel and put a dwarf against me. I had an army of approximately the same strength as the enemy, but I only had 20% additional damage from counterattacks, while the dwarf had almost all the runes, which he used until the end of the battle, when he hit me twice in a row, and I missed him, it seemed that there were no chances of winning, but I still managed to win that battle. In terms of magic, the enemy also surpassed me; I hit him with a simple attack, and he hit me with Divine Retribution. As for other factions, the situation is similar: a mage with 50 knowledge can give his troops a +13 attack, defense, and 50% initiative; an elf can deal colossal damage with luck and critical hit damage; a barbarian can give his troops a lot of health, which is not so easy to reduce in an Uber-fight. However, despite all this, the knight can defeat them. So, the main question is, what is the strength of humans that allows them to overcome what seems to be a much stronger enemy?