The predominance of the invaders’ males lineages suggests that native males were killed off.
It could also indicate that they new coat of paint, as it were, was nearly completely male, or that they tended to have larger families, and/or lower infant mortality. They may just have been preferred as lovers, or had a little more, uh, gas in the tank as it were. For that matter, the preceding Beaker People men may have been polygamous, and not all that numerous.
The invaders had horses and swords, the natives didn't.
They killed all the men and took the women.
Exactly. And the “invasion from the (cold) eastern lands” just like the mongols later across Europe, and the huns, visigoths, vandals, etc after the Roman Warm Period.