Round table

What do other resources and their rules have to do with it?

It's very relevant. If you study any rules, you'll see that they all support the spirit of competition. Any contest implies rivalry. It doesn't matter how the situation with 1 fly and 100 golems will be interpreted on other resources. A person playing according to the rules of a particular resource reads those rules and knows what the outcome of the situation will be. And the interpretations of the rules clearly imply a struggle, not standing in trenches, and they predetermine a decisive outcome.

A simpler example of a similar situation: a battle between two level 0 heroes, each with an angel, neither has any armor or offense, one of them has the "Spirit of Despair" spell, in the first round each attacked, the angels are left with 100 HP each, and now tell me, who in their right mind would attack first in this situation?

Who in their right mind would attack an angel with an angel when the possibilities are equal? I've never encountered a description of such a situation in practice. And in theory, you can come up with all sorts of trolls and weaklings. I can imagine a "gopnik" attacking another "gopnik." But that's not the point. Any contest is accompanied by sportsmanship. Either you win, or you lose. A draw is possible, but the Heroes interface doesn't provide for that.
And the situation with the fly and the golems is interpreted in a predetermined way on all resources. Only on Heroes Wiki is it something vague. And the slang term "fly" cannot be used for the rules. It's a different matter if a computer with a hundred golems attacks a fast level 1 unit. I haven't encountered this in practice, but it's easy to imagine.