It does look very dark. Whitewash it? Paint with Romabio (brick limewash)?

Paint the firescreen black.

Remove everything but 3 items from the mantel.

Remove everything from the mantle. Paint the brick and then reassess. I’d consider adding a nice chunky wooden mantle that spans the fireplace.

Sorry..should have added..(and why can’t I edit comments??) replace the fireplace inset with something more modern, maybe matte black. The mantle would span the width of the section around the firebox.

Unless you have more flooring stashed somewhere, you don't want to remove the hearth. I would paint it all black with a satin sheen and go for a striking look. Every room can use some black. Add a larger piece of art and put a candle lantern on either side of it.