Can you hit mobs only once?

Hi

I got Minecraft yesterday and now I have the problem that I only hit mobs 1 time before I have to press the left mouse button again. But dismantling and blowing in the air is easy?

No, that's how the combat system works in Minecraft. There are certainly a few mods that make it possible to simply hold them down, but this is not possible in normal game.

Certainly.

What determines?

There are definitely mods for it.