Your last sentence is bang on, and if Catholics truly read and only went with what the Bible teaches they wouldn’t be Catholic.
You can point out it all day long and they’ll just dig in deeper.
For me, when Jesus died on the cross for me, it was enough, it was the perfect gift, and nothing else is needed to earn my way. I don’t pray to any dead people, I pray to Jesus himself. I don’t need any other intercessor, for Christ himself is my intercessor, and he’s the only one.
I realized a long time ago, that anything you add to the finished work of Christ on the cross is what you’re REALLY trusting for your salvation.
So if it’s baptism, you’re trusting the baptism to save you because Jesus won’t or can’t without it.
Same with communion, confession, penance, saying the rosary, confirmation, *corporeal works of mercy*, last rites, whatever.
Actually, the Holy Spirit also interceded for us according to the will of God. Romans 8:26- 27. So we have both on our side.
It doesn’t get any better than that. Who needs dead people praying when Jesus and the Holy Spirit themselves are praying for us?