Souls that never heard of Christ

One should bear in mind the context within David is talking. He's being chased by Saul and his life is at risk. This is when he starts writing his pslams to God about his current situation and at the same time he is being prophetic. To David, when he was talking about being saved from the grave he meant being saved from his attackers. But at the same time he was, and I believe unknowingly, alluding to how Christ will literally be raised from the grave.

That is an incorrect application of that passage

Why so?

No you dingus, that's psalm 57
Psalm 49 isn't even written by David

Either way your attempt to explain away David knowing his baby would be with him in heaven is falling flat

If you read pslam 22 you'll see David talk poetically about his situation and it's not even what happens to him. He speaks very literally but actually has metaphorical meanings that find their actualisation in Christ.

Also, going back to if babies can go heaven. As of now I don't know but I lean towards babies going hell. I see no reasons to believe they go heaven but every reasons to say they do but then again the scriptures aren't explicit so like David I do not worry and just trust that God is good.

There's nothing to indicate that he believed that the child will be in heaven. Rather he is just saying that he too will go to Sheol where the child is.

Because it's a passage that uses hyperbole to heighten it's point. To take it literally wouldn't make sense. We all fall short, yes.
But you cannot say no one seeks the Lord and speak truth if you mean it in a literal sense.

That's based on the assumption that David didn't know about eternal life, which I think is clearly inaccurate.
Psalm 23 "I will dwell in the house of the Lord forever"

You only assert this because you presuppose babies go to hell

Eternal life was understood differently in the Old Testament

Show me an insufficiency in any statement of David regarding eternal life