Yes, definitely, God really cares for us. It is said in the Bhagavad Gita.

ananyāś cintayanto māḿ ye janāḥ paryupāsate |

teṣāḿ nityābhiyuktānāḿ yoga-kṣemaḿ vahāmy aham ||9.22|| But those who always worship Me with exclusive devotion, meditating on My transcendental form—to them I carry what they lack, and I preserve what they have.

He declared that he will care about the people who worships him.

Now, the question why Muslim invaders not punished for their massacres can't be answered by facts because we don't know what happened to them in their personal life after they did these invasions and massacres is not well documented. But they will be served their Karma. But we don't know when and how.