You are 100% correct.
We owe all to the grace of God and not by our rightousness.
The Bible made it clear that our rightousness is like filthy rag befor God.

Isaiah 64 vs 6

But we are all as an unclean thing, and all our righteousnesses are as filthy rags; and we all do fade as a leaf; and our iniquities, like the wind, have taken us away.

It's only by his grace we are saved.