Never mention a song of ice and fire!! Martins writing style is pure shit, and his story is going no where. I hope he dies before he finishes the series.
Cain survived those encounters he didn't kick their asses.
Space marines are the best of the best, but now a single space marine isn't good enough compared to some figures. Even with being genetically superior with the best weapons against something like a big tyranid, they are screwed.
So it's becoming increasingly apparently that you know fuck all about 40K.
Space marines are super soldiers they are no where near the best of the best.
Genestealers destroy them
Necron warriors weapons are more than capable of wiping them.
the tau are more then capable of beating them.
Plenty of astartes die to eldar as well.
Orks are also more than capable of wiping astartes as well.
They win because of they can shoot straighter and hit first allot of times. But other than that they die. Because they don't fight smart. Nearly every space marine novel goes like this.
Bad guys appear,
space marines respond,
fight to a standstill
war begins to turn against them.
war turns in their favor due to a wildcard.
war is won by a tactical strike.
Cain never charges into battle alone, he always ensures he has troops around him. He also chooses his engagements and he always tries to find a way out.
In the greater good cain dropped his weapons when confronted by that battlesuit. A space marine would never have done that.
It in turn caused the tau and the imperium to gain a truce.